I Have A Bad Back And Have Mussel Spasms Regularly,

I have a bad back and have mussel spasms regularly, but for the past week I have been having very severe spasms ( charlie horses ) in my feet. They hurt so bad I can't even massage it out for several minutes because it hurts so bad. they remain very sore for quite some time after they happen. I was wondering what may be causing them. I have have had "charlie horses" in my toes before but they are few and very far between, it has been so long ago I can't even estimate how long ago the last one was and the didn't hurt anywhere near what I am experiencing now. Actually those were kind of funny. I have had 2 in my left foot that caused my foot to curve inward to the inside on my leg. It really has me concerned.