Medical board certificate for time extension in universities exams due to Fibromyalgia

The MG UNIVERSITY Kottayam, Kerala, sends me a mail upon requesting for time extension during my exams , so they replied in the format below - " BRING ORIGINAL MEDICAL CERTIFICATE IN THE MENTIONED FORM AS GIVEN IN THE ORDER ATTACHED FOR GETTING SPECIAL CONCESSION " . So I decided to apply for a medical certificate at the medical College, it was today and they are now clearly refusing to give me the certificate on the basis that , My condition" Fibromyalgia " can't be used as a reason to do so , and they are also rejecting my Discalculia assessment because I'm now 19 years old , they are saying it's not valid. Now what I should do to get time extension. The university gives special concessions on the basis of RPWD act 2016 , but today the doctors from Neuro Medicine, Psychiatry, ortho are saying Fibromyalgia isnt a disease that would get you a concession, for god's sake I have been treating for it there for the past months and they are not willing to provide any help further , my exams are coming near , I don't know what to do