Hey Antonia! I remember during my worst pain just doing every thing I could to not move my arm at all. Driving was difficult, but I couldn't just take off of work. The PT was difficult as well, I sometimes just had to tell the therapist "this hurts too much!" and he would change what I was doing. So don't be afraid to tell them if it's too much. It's a very frustrating injury, you just have to know you WILL get over it and it WILL get better.
My injury was unique. It was due to a reaction from an antibiotic called Levaquin. It was a long road to figure out the connection, but it seemed like more than a coincidence that after taking Cipro several years early (same family of drug) I wound up with bad tendonitis in my hip and went through PT as well. In both cases the orthopedic doctor couldn't figure out WHY I had my injuries! One of the "side effects" of these drugs they conveniently don't tell you about is tendonitis and even possible tendon rupture! I think it gave me tendonitis and then from continuos use and a few rounds of normal golf.. it wound up with a tear. Just make sure you take your anti-inflammatories regulary to help out and don't be afraid to ask for narcotics if the pain is that bad, I had to!