I found this post on one of the Parkinson's forums sometime ago and saved it to my notes (don't recall know which forum was it):

" You can try several things. I would suggest trying only one at a time, and try it for at least three days to insure it is or is not working. First, try the supplement: magnesium (at least 250 mg twice a day). Second, try ice packs on the offending muscle group. Third, try taking gabapentin (350 mg by prescription). Fourth, try sinemet 25/100 mg by prescription. Fifth, try a TENS unit. All of these worked for me at different time. MM"

I have occasionally bad cramps in my calves and bottom of my feet but didn't try any of these suggestions, yet.