Have you tried ice and hot pads? maybe you need to do some stretching as when I do really long rides (12 hours) I get a stiffness from my shoulder to the neck. If stretching does not ease the pain then I also would recommend acupuncture, (my doc is great and applies a little electricity just for fun!! )Hope this problem clears up soon.do not leave it for too long to get seen to if it doesn't!!! happy pain free riding