I had thus problem in past, though not so severe. It's annoying and tiring. Since your it's so severe, I'd consider taking a med, though I understand your worry at the idea. Also, one method could be, reread maximum 3 times and then stop, though you aren't sure that it's enough. It's hard, but I did it for other symptoms and it's a good method. Or at least, stop rechecking for that day and give it a look the following day just before the class. Try to persuade yourself that if you already checked 3 times and didn't change anything or very little, your work can't be improved more.
Another idea: have you a friend or family member that could read your work and assure you that it's ok?
Good luck with everything