I completely feel your pain!!! You just described this whole academic year for me. I'm usually really good with balance, but with being sick on and off really badly since september, things are so unbalanced.
I tried talking to disability services to which they told me that b/c I could walk and talk I was not "disabled enough" for them. Oh yes, that is verbatim. Not to mention I had gone in there 2 weeks after my second hernia surgery! They wouldn't even give me temporary parking!
I know what you mean though, some professors are SO understanding and others are just big dopes. One professor actually asked me to have my doctor CALL him b/c he didn't believe that one person could be sick so much. (Umm yea the IV in my arm wasn't enough reason for him lol )
GOOD LUCK and I REALLY hope that your school can accomodate your needs but you should absolutely look into what they can do for you!! As for that professor, tell him that you'll be taking the matter up with the Dean (or President) of the school/department. He may change his tune with that put out there