Muscle spasm after ACL surgery.?

Ever since I had reconstructive knee surgery to repair my ACL/MCL and meniscus in December, I have had very painful muscle spasms at night. It doesn't occur every night but when it does, it only happens in my left leg, which is the leg that i had surgery on. It is usually in my calf. When I have a spasms, it feels like my knee is moving and it is very painful in the morning. I had an x-ray and my surgeon said that my knee is not moving or shifting.What should I do? Has anyone else had this problem?