Hey Ankur,
As of now, it will be hard to say what could be the possible reason until we do physical examination and proper assessment. But, try with some simple exercises and stretches. Especially calf stretches, hamstring stretch, static quads and hams, etc. Keep your body hydrated and drink plenty of water, fresh juices to maintain proper hydration and electrolyte balance. Get sufficient amount of sleep. In case, you have severe pain consult your physician and get necessary check up done.