Have pain right leg 5 days. ultrasound negative for blood clots.if swollen not a lot, not red just achy pain in thigh now calf what could it be?

May be muscular: Besides blood vessels and nerves in extremities, there are a lot of different muscles. Overuse in exercise and athletics are common causes for achy pain. If pain localizes or persists for prolonged time then other investigation as to etiology is necessary. Sometimes MRI is necessary. Very important that ultrasound was negative for blood clots, a serious situation requiring immediate appropriate Rx