Hi there...there are many different causes for pain in the leg. It depends on which part of the leg it is affecting and when the pain is aggravated. Diseases like venous insufficiency are very common where increased pain in the calf is noted during nights. Also diseases like arterial insufficiency, disc prolapse, abnormal posture causing muscle strain, rheumatoid arthritis, osteoarthritis alos can cause such pain. It will need detailed clinical examination and further investigations, probably venous doppler. So kindly consult a nearby general surgeon and orthopedic for further evaluation.