Severe muscle knots

[Newstart20]

A couple of years ago I developed severe pain in my shoulder, which felt like being stabbed with a hot knife. This has continued since then with periods of some improvement. I have tried heat/cold, different painkillers, lots of rest and regular sessions with both a sports massage therapist and an osteopath. I literally cannot get rid of it regardless of what I try and when mentioned to the GP it was brushed aside.

Any ideas of what might be causing it and how to treat it more effectively?

Same here. It took about a year for me for it to get better and then it went away only for it to come back again last year! I realised that it was the way I was sleeping on my shoulder that was causing it.
I still can't seem to adjust myself so I'm not lying on it so I've pretty much resigned myself to having the pain forever. Not what you wanted to hear probably but I'd look at mattress, pillows, the way you sleep or hold yourself during the day. Have you got TMJ? That can contribute to shoulder pain.

This is one of the things that yoga has helped me with. I think the improved muscle tone has held everything in place and my shoulder muscle knot has gone. It used to cause me pain, along with my knee and pelvis. I would see a chiropractor every month. Since doing yoga, all of these issues have resolved, along with no more pronation. I haven't had to go the chiropractor for 8 months now.