Have you looked into Family Medical Leave? My understanding is that they have to hold your job for 16 weeks. Again you would have to have a Dr. sign the form stating you have a medical reason to be off. This is a law used to protect your job while having to be off for medical reasons. The short term disability is something that pays you why you are off. Sounds like you need to discuss with yur Dr. why he would not agree that you are not able to work while in treatment.