Yes MS could cause the feet to cramp, but so could a lot of other things.
If you currently have MS then this could be the reason why.
If you havent got MS then, you need a proper blood work up, checking for rheumatoid arthritis, also a full vitamin and mineral, pottassium, etc blood tests,
You may have too much or to little of a certain mineral, vitamin, etc, which may be causing the problem.
Hope this helps and good luck
Have you tried quinine when this happens?