UM let me give you one more academics perspective. To hold a spot in a class preventing another student from taking the class what ever the reason is very incosiderate. It could easily cost that student another semester or even a year in school if it was a seqential class. That could cost someone their entire education. If it happens to one if your departments advisees, who happens to be liked, you will have trouble the rest of your career. Most registration happens the semester previous not days before class starts. its your responsibility to know what you are getting into.
"Accomidations" are not situational.and need to be taken care of well before class starts. While certain disabilities lead to particular accomidations, academic integrity will never be comprimised. All your work has to be done, done to standard, attendence matters, practcum hours matter. If you can't do it then "try something else" is appropriate.
Understand though, I was preparing students for a field where, you would not want accomidations made and the proffs ruthless.
Living with a chronic illness is tough, but the fact is most people have something going on in their life. And while they may give you sympathy or understanding, it is short lived.But what you get from any relationship, professional or otherwise is proportional to what you give. When you say nobody cares or understands you correct. The best thing you can do is make sure you understand.