Ling,

I experience something similar -- I get terrible foot pains during my OFFs. I had originally though they were cramps, but no muscles were actually cramping. (strange but true) I later figured out I have Neuropathic Pain - burning-shooting-excruciating pain in the nerve endings of my foot. I can tell when I need to increase my pd meds - the pain increases in frequency. I try to take as low doses as possible, but when I can't stand the pain any more, I know it's time to add some.

good luck