Re: GP didn't even give referral
It is possible you have arthritis. And it's true some surgeons are a bit single-minded: "You're not a surgical case, don't let the door slam on your way out!" BUT:
1) You don't know what the problem is, so you don't know whether or not surgery is warranted.
2) The good orthopedic surgeons take their time, consider all options, and try conservative treatments first.
3) If nothing else, you can get scans and, more importantly, have the scans read by someone who knows what he's doing.
A few additional thoughts: There are a lot of chiropractors who are quacks and do more harm than good. Some are great, but many are not.
The pain spreading out from the shoulder kinda resonated with me. I get muscle knots that tie into one another. A knot in my shoulder can trigger pain in my neck, head, jaw or finger. My jaw pain comes from cheek muscle spasms which connect to neck spasms.
You say the muscle is softer. My first guess at why would be deconditioning--if the shoulder has been hurting that long, you probably don't use the arm as much. Which is what any sensible person would do, avoid activities that are very painful.