What's an effective treament for a cramp in my foot?

Foot cramp: First is to find the origin of the cramping to prevent it from happening again. Sometimes stretching of calf muscle helps take pressure off the foot, also hydration and healthy diet is a must to prevent foot cramping. Lastly, massage and icing to help ease tension and contraction of those intrinsic muscles. Try off-loading with inserts or see a specialist for custom orthotics. I hope this helps.