Hi tigertelly.
I get these awful muscle spasms as well. They were getting to the point were like you it was effecting my everyday life and not to mention, very painful. (I had a two level spinal fusion three years ago so all do do with that)
Last October I went back to my GP who has prescribed me Amitriptyline, normally prescribed for depression. I was a bit dubious about taking them but I have to say it has helped enormously. I take one, or if it's bad two,every night. 10mg tablets.
It helps the muscles to relax and not get so tight and painful.
But as Sqad and jackthehat have said, really need to know why it's happening.