What Causes Persistent Pain In The Shoulders?

my shoulder has been hurting for the past year and a half. at first it felt like a strained muscle, i felt pinched in towards the back of my neck and around the edge of my shoulder blade. and now lately in the past two months or so it feels like it's in my bones or my nerves, like the pain will come from my neck right on top of my shoulder then go down my arm in almost a line but a general area line and into my fingers. and it's going into my other should now, and sometimes it goes into my legs too. i've gone to physical therapy for when it was just my right shoulder then it didn't help so we stopped and a little after that it got worse.