Q:

Piano exercises post-chemotherapy

Not a common question, not a common situation, and I am not using my primary Music.SE for obvious reasons. The question is simple but not so easy, and I hope you might help not only me, but many with this experience:

What exercises can I do now, after finishing a long chemo, given that I have numbness and tremors in my arms?

Longer explanation. 
Many cancer drugs have neurotoxic effects, this means that you might, as I did, finish chemo and you experience numbness in your fingers, tremors in your arms (and legs). Depending on how much nerve damage you suffer, you still can write by hand slowly and with your calligraphy, no precisely and neatly as before obviously. 
Trying to play results invariably in two distressing outcomes. You're very slow, and you're very imprecise mainly in pressing the right keys rather than in rhythm. I was at a level where I could almost play some basic Bach pieces (minuets, prelude in C, yes I am a beginner), and now I am unable to play them at all at the same level. I can still play single keys and chords, again not precisely, so I make mistakes placing fingers (for instance, a Dmaj might end up in Dmin because my finger trembles and ends up on the lower key instead of F#). Moreover, I had to abandon lessons with my teacher, and I won't be able for some time as I won't go back to work soon.
So, what can I do during this period?
I know it is unusual, but cancer happens, and I hope other people could benefit from this question. Maybe even here somebody had this unpleasant experience, and have good recommendations for overcoming difficult times.
Edit: added some details based on your comments and answers.
Updates

A brief update after few months on what to expect in playing the piano after chemo.

As I've been pointed out, playing is counterproductive. I can only say that it is particularly true, especially if you had a platinum-based chemo, or other neurotoxic drugs. 
The neurodegenerative process will continue for at least two months after your last chemo, so tremors and numbness (effects of chemo on the peripheral nerves) may continue to grow depending on what drugs you had and of course, on the dosages (high doses, in my case). 
As for confusion and difficulty to concentrate (effects of chemo on the central nervous system), after three months it wears off, be patient and take your time... but back on the playing part. After two months I could follow a score with music, so that's good.
Nerves take a lot of time to reconstruct, a year and even more. I found possible to play but really frustrating with pieces that are not mechanical, for instance I can play Hanon (yes, I know), but since I hate it I try to avoid playing it.
Just one advice for those in my condition. Please don't try to stress your muscles, your tremors will only worsen due to nerve exhaustion (they get tired, too). 

A:

May you have a timely recovery. I have not had a similar experience so I will write generally.
Here are some activities you might pursue during this period.
Playing
In my opinion - and opinions may well differ here - in your present state it would be better to leave the instrument alone for now. I see the potential for a lot of wasted time. In teaching your body to play in its present condition, you would learn patterns and coordinations that you won't use when you have recovered. Playing will feel different, and playing musical instruments is largely based on teaching your body the feeling of producing the desired sounds. If the feeling changes, so do the sounds. I don't see any useful technique you can learn for the future, only compromised technique that you would need to modify or even unlearn entirely.
The rest of my answer suggests improving your general musicianship. Most of these activities will indirectly benefit your playing.
Listening
A little time spent actively listening, along with the score, to music you like and intend to learn will be well spent. This can develop your memory.
If you like orchestral music, or chamber music, download the score on IMSLP and follow along. Score reading skills improve you as a musician and build confidence.  Knowing music other than that for your own instrument enriches your playing.
Written Work
I needn't mention composition as an option: if you have the inclination, you're doing this already.
If you ever intended to take any theory examinations, now is a good time to download some specimen papers and try them out.
Only interested in playing? If you've never done it before, why not buy some manuscript paper and copy out one of the compositions you had been playing? Transpose into another key, if you like. Try to hear what you write.
Some famous performers believed religiously in the hidden benefits of copying scores. Copying a huge number of compositions at a young age didn't seem to harm J. S. Bach either.
Software
It may be useful to teach yourself a notation package. For my work LilyPond is best suited, but there are plenty of others you can readily find.
Those with GUIs generally allow you to hear the music you have entered. This can be an easy way to take baby steps in composition, or just to learn about arranging and orchestration.

A:

Simply stated, but a difficult question. I have never experienced cancer first hand, though I have had family members who have. That said, I have been in situations where I had to play piano with very cold hands.
This sounds rather mundane I know, but it can be a problem for pianists - the hands are lethargic and unresponsive. And as obnoxious as it sounds, I don’t know of any exercises you can play to specifically warm up the hands (I’m talking really cold here, far beyond the average “warm up”). I also don’t know if there are exercises to overcome neurotoxic effects of treatment either. 
However, in reading your post, it sounds to me as if, for the time being, two things should take place: 
1.) It’s important for you to be compassionate with yourself as you move through this process and not get hung up on the things you “used” to be able to do. It’s also important for you to recalibrate your goals / expectations for the time being so you can achieve small rewarding goals here.
2.) If you can, I would highly recommend seeing a physical therapist (even just a single consult) to talk about strategies for gaining control of your arms / fingers again. I would also highly recommend seeing a musical therapist to discuss strategies for creating a successful approach to Piano. 
Assuming the effects from the treatment are temporary, then you’ll be able to use this time to re-train your arms and brain, re-establishing your foundation.
Besides all that, it might be worth playing pieces from children’s books, or to just settle in playing through your current rep slowly. I have found a bit of a tempo “wall” with cold hands, so it would be curious to see if you also experienced a tempo “wall” (a speed at which you can’t play faster). Difficult to assess without seeing / hearing you, hence the impetus for my recommendation to see qualified people.
Please update us on your progress, and I hope something I mentioned here was useful.

