Hi @Bel1 and welcome to the forum.
I can imagine how difficult it would be to study while you're experiencing that kind of exhaustion. I would be tempted not to take my medication also, though I am guessing that not taking medication may cause different problems. Are you able to see your doctor sooner and talk about changing medication earlier?
I am not studying at the moment but but it is something I am really hoping I'll be able to try again sometime. There are a number of people here on the forum who are studying who may be able to share their experiences. It might be worth posting a new discussion so that others can see your post easily and respond. You can do that by clicking on "new discussion" under of the discussion topic headings if you'd like to. You might also like to introduce yourself here, which can be another way to meet members who might have the same kinds of experiences.
Best wishes with it all. Hope you find something that works for you soon.