Over the last week I have been getting very strange cramps when I work out or play tennis. I haven't had cramps of any sort for several years and I am in good shape. There isn't a strain or injury that I can pinpoint these to. The strange part is that they happen very, very early in the match or workout - just after a few minutes of playing or working out. They are pretty intense leg cramps - the outside quad muscles will fill with fluid and tighten up and then they may ease up some, but are still there at some level for the rest of the day. This happened twice over the last week while playing. Today I was working out on the eliptical machine when the muscle just above my knee more on the inside cramped up after 15 minutes, which of course is very early in a workout, which was a normal one. I cut the workout short after really slowing down. The cramp eased a little after the workout, and I've stretched my quads a lot after finishing. The muscle is still tight - I can feel it with my finger and tell that it's tight from the outside even. Has anyone ever experienced anything like this? I don't think it's from lack of stretching, or not being in shape, or overuse of muscles. I am wondering if my diet might be lacking something, or if I'm eating too much sugar, or something along these lines. . . any advice is appreciated.