Sometimes, my calf starts to hurt extremely bad. in one of these moments, i felt my calf and i felt movement. what could this be?

Leg cramps: These are sudden contractions of a muscle due to lack of stretching, inactivity, or an electrolyte imbalance like low potassium. When it occurs, stretching the calf muscle often relieves the cramp. Prevention is not exercising after eating, gently stretching calf before bed, drink plenty of fluids, & not consuming caffeine, nicotine. Pull your foot/toes upward can help stop the cramp. See your md.