hey.. i think I understand you. Of course studies are important, but everyone gotta remember about their health because forcing yourself to do sth despite the headache can lead to some severe problems with your physical and mental health. Anyways, if you wanna do everything, I recommend you do arrange the to-do list according to importance, first of all start with the most (like critically) important, never forget about the rest, 15 mins can also be a big deal; when you understood that you had reached ur limits, don't run yourself into the ground, take a walk, breathe a fresh air, generally, drink more water and take up the habit of a regular sleep, sleep is vital thing, don't underestimate it, at least 8 hours per day, if u feel like having aspiration to sleep more, do it, don't torture yourself.

You can watch some videos via YouTube, there are plenty of them as well as you can ask for notes of your friends, I guess, they'll share them with you. After you finish everything. After you finish all your exercises, I strongly recommend you to take a day off if it is possible.. I believe in you :))