Every doctor says something different...

Symptoms: I've been having upper back spasms and constant shoulder blade popping since I was a 8 years old (I'm 24 now). When I wake up in the morning, my shoulders make a sharp 90 degree angle from my torso, and no amount of massaging will relax them back into place. Being on a commercial airliner is the WORST because I'll go to sleep in the tiny, cramped seat and wake up in excruciating pain with my left arm numb and my fingers contorted into a creepy-looking fist. Right now, in both shoulders, I have several rock-hard knots under and above my shoulder blades that cannot be massaged out. It's painful enough to affect my work, and I've had to go home due to the pain and headaches before.

The "causes:" The orthopedic tells me it's my shoulder blades rubbing up against my ribcage; the physical therapist tells me it's loose ligaments in my shoulders, and I need to strengthen them; and the massage therapist tells me it's severe muscle knots. I'm tired of going to doctors who tell me my problem lies in their line of work. I've had slight improvements with the physical therapist, and I continue to work my shoulders out, but nothing else has helped in the slightest, and the problem is far from solved.

My sister has similar back and shoulder pain, and she's been to a chiropractor who says (surprise) that her spine is twisted... Not sideways like scoliosis, but twisted as if someone grabbed her spine and wrung it like a wet rag. It's apparently about 14 degrees off, and she's going to sessions to fix it. The interesting thing is: so far it's working.

So: is this a common problem, or has anyone had it before that can vouch for going to a chiropractor? Do I need an MRI?

Thanks for any help/advice!