I agree with elin wee... what examinations have been done on your shoulder.
For example, if you have a tear in there, it might aggravate the pain whenever you use it and not really get much better.
21 weeks is way too long.
I think 3 months is long - i am a fan of seeing improvement (not necessarily complete recovery) in 6 weeks. Otherwise my patients get sent to the orthopod.
Find someone who is more proactive. I think you know in yourself what you need, perhaps you are looking for permission to go look for answers? I get the feeling you feel more should be done about your shoulder. I agree - i would start at an U/S scan orMRI.
Cheers