officially diagnosed with IB, applying for GRE accommodations

[robertrulez]

So I saw a new GI and he basically told me I'm suffering from a classic case of Irritable Bowel. As it is counted as a disability by the ADA, I was wondering what is the most effective way of asking my doctor for a letter so that I can apply for accommodations for graduate examinations. He seems very caring so I don't think he'll object, but I just want to be prepared for the appointment.

I'm specifically asking for extra time and breaks between sections, I'm just scared he'll think negatively of me and not write me the letter.

 

Also has anyone else had any experience applying for accommodations and can give me pointers in making the strongest possible case?