What Causes Muscle Spasms In Back And Cramps On Feet?

I have been having muscle spasms in my back for a few months and right side pain.i went to my doctor about 4 months ago and she said I could have pulled a muscle.she gave me some muscle relaxers. I don t think that s the case.what should I do next? My sister works in MRI she thinks I should have a CT done. Also I have been having cramps in the tops of my feet.