How to ask a teacher for an extension? I failed an exam last year and now I am retaking it but in a different format. 
Everytime I sit in front of my laptop to write the assignment I have anxiety. My anxiety is mainly caused by the fear I have to fail the exam or the fear to make the things wrong. The anxiety probably depends also on other reasons(I have a chronic disease plus other families related problems). I did not say anything to my teacher about the anxiety because I don't want he thinks I am using the anxiety as an excuse. 

The problem is that I already asked for a small extension but now, I realized I need few more days. What should I do?I am spending all my days crying because I am stuck with this assignment and I cannot procede. I have the fear of the deadlines, I always wait the last days to finish an assignment because of my menthal status and the medical treatment the doctor gave is not helping me as I am feeling sleepy the whole day.

I don't know what exactly to ask to the teacher...If I can say the truth(stress/anxiety related problems) or if I can tell him that I need few days because I would like to achieve better result without talking about my mental status(which is something I need to fix as soon as possible).



Update 09/03/2020: I didn't receive any answer from the teacher :( I am feeling really really bad
Most universities have an office dedicated to helping students deal with disabilities of various kinds. Perhaps you should visit them. They can probably help with stress reduction. In extreme cases a doctor's help might be needed. 

But, you might also consider asking your professor for an alternate way to take the exam than online. Perhaps taking it on paper would be helpful. Perhaps having someone else in the room with you would be helpful. But think about more options than just additional time. There is something going on in your life that suggests that time, alone, isn't the issue. 

Even an oral exam is better for some people, though not everyone. But it requires a certain amount of empathy from the professor that not all will exhibit. 

But if you need to ask, do so in person if at all possible. It is more likely to be successful and the professor might be able to suggest alternatives that won't come up in an email exchange.