Regarding illnesses and how to make a note of it with my school.

Between my mental illness and the hyperthyroidism, I've been physically sick (probably mostly due to my anxiety more than anything) and mentally just all over the place. So I have fallen behind on school a bit and have missed some classes. It's nothing I can't catch up on, thankfully, but still I've fallen behind.

I'm setting up appointments to meet with all of my professors one on one to discuss everything in detail and bring in documentation from my doctors for them, and to inform them that I may miss more classes in the future as I'm going to be trying new medications soon and I don't know how I'll react to them (for reference, when I went on Trileptal for my seizures, within a few hours of taking one pill I was so ill that I had to go to the ER. Good times).

But I was wondering if I should speak to some form of administration at the school about this? Just to have everything on file in case a situation arises with a professor where he or she is less than understanding about the situation. Do I speak to the Students with Disabilities center? Does what I'm dealing with count as a disability? I just don't even know. I just want to make sure my professors know I'm not missing class or falling behind because I'm lazy :/