Often times when it comes to pain, the cause can be psychosamatic. My sister is in her final training for massage therapy and I would HIGHLY recommend you find the very best and most experienced therapist you can and see them on a regular basis for at least a couple weeks to a month to see how it works for you.
Stress can build up over the course of your life and things you take for granted (sore muscles, stiff joints) can build up to the point that... well, to be "technical", everything is outta WHACK! Seriously though, massage therapy, accupressure and accupuncture are bone fide treatments and I'd bet real money that what doctors aren't seeing in their tests is something mental/spiritual and not nessecarily physical.
I wish you luck in your alleviation of pain. Keep an open mind but also seek out practicioners with creditials and good word-of-mouth.