sounds like you are low on potassium could be from taking the predfoam.
I got/get wicked bad foot, toe, calf and thigh cramps when on pred orally. To combat this I eat a banana a day and when on high doses of pred I was drinking fortified juice w/480mg of potassium per 8oz serving 2 servings a day plus the banana and that really helped.
I'd start out w/a banana a day and see how that goes. Local banana's mmmmmm!