Foot cramps or spasms can occur suddenly and with no known cause. Some common theories as to why they occur include abnormal levels of minerals or electrolytes in the body, dehydration, kidney disease, thyroid disorders, certain medicines, and brain disorders such as Parkinson's disease, multiple sclerosis and dystonia. Muscle fatigue in the feet, numbness and tingling, twitching, rapid motions and tightening of the muscles are all common symptoms and can range in severity. Most cramps or spasms are temporary and will go away on their own with rest, stretching and hydrating. If these episodes continue to occur frequently, then a doctor should be contacted to test for a possible disorder or deficiency.