After my PhD supervisor left, I was assigned to a new PI who has little experience in my area I am halfway through my PhD (given 3-year contract) and I feel I'm in my worst phase. The PI (let's call this PI X) who recruited me as a PhD student left my institute for a better position somewhere. Before X left, X assigned us (Ph.D. students under X) to a new PI in our department who is not yet all experienced in the work I'm doing. Once in a while X is talking to me through skype but now X seems to be mainly interested in authorship of the work we have done together and also a project we planned to do. 

The main problem I'm facing now is, I don't have anyone to give me feedback on the analysis/interpretations I'm making from the data. If I don't get any critical comments/feedback on my work, I'm feeling I'm not learning anything new. And, this will also be a problem in the long run, when I make my work into a manuscript. Our department head, who recruited X seems to care about the situation but I didn't discuss it with him. As I have this new PI (who is also recruited by dept. head), if I discuss the situation with the department head, things will get more complicated. I know as a PhD student, I should be more independent but if I don't get enough feedback on my work, how can I improve my critical thinking.

Any suggestions on how to deal with the situation is greatly appreciated. I can provide any additional information if required.

Thank you.
I don't understand why this sentence has the word "but":


  Once in a while X is talking to me through skype but now X seems to be mainly interested in authorship of the work we have done together and also a project we planned to do.


Without the "but," that would sound great!

In principle, your choices are:


Transfer to X's new institution
Stay where you are but continue collaborating remotely with X (with lots of email and some occasional phone calls and video conferences).
Allow yourself some travel to where X is for some in-person collaboration (this has to be done with consideration for X's schedule and preferences, of course).
Talk to the department head and ask for advice.
Talk to someone else in your department and ask for advice.


Another thing you can do is basically choose option 2 (and perhaps 3), but try to be more independent than before, so that you don't need to take up so much of X's time.  Here are a couple of tricks for doing that: 


Have a dialogue with X in your mind, where you lay out a question, and then you imagine the discussion that would ensue with X, based on what you know of X.  This works best when you're almost asleep.
Rubber duck your problem with a good listener, as programmers do when they're having trouble finding a bug.  Walk the listener through the background to your question, and the question itself.  Often, going through this careful exposition with a human being who at least looks like he's paying attention will get you unstuck.