I had the same experience as Insty did. I refused an MRI because I had zero interest in shoulder surgery and there is no point in paying for a medical test if you have no intention of doing anything about it. (Yes, I pay for my medical care.)
I did not bother with physical therapy, rested it from tennis and weights for a year, and it's pretty good now except that I have had to replace my fast serve with a spin serve - which is probably more effective anyway. It gets sore after four hours juggling a chain saw, but that's ok with me.