What Causes Muscle Spasms On The Back?

For the last 3 weeks I have felt achey, the feeling at the beginning of the flu, except no other flu symptoms. For a long time now I get muscle spasms every day. I mostly get them in my back between the shoulder blade and back bone. I get them several places including my neck. I was once diagnosed with Lupus, but labeled as a Mixed Connective Tissue Disease because of the ANA test, joint pain, false positive syphilis and Raynaud Syndrome. I was diagnosed over 13 yrs ago, went to a rheumatologist for awhile til he went off insurance - then just stopped. Funny though, no doctor has really brought it up - not that they would I guess... anything else it could be? Maybe just arthritis?