Lilly... How long have you had this problem? It could be related to stress as Laura said. It could be related to a simple magnesium deficiency causing muscle spasms. Once the muscles tighten up, they can cause the cervical bones to come out of alignment and then you have a pulling on the muscles because of misalignment. Try supplementing with a magnesium supplement like magnesium gluconate or taurate. Soak in an epsom salts bath. The herb Kava helps relax muscles too. You can get kava at a health food store like Vitamin shoppe. I used to get really bad tension headaches caused by muscle spasms in my shoulders and neck. Kava and heat helped loosen the muscle spasms. Supplementing with magnesium got rid of the problem.