Suggest Treatment For Leg Swelling

Hi, there is a swelling in my right leg from 4 days. I thought it was a nerve problem and will be fine soon. In the evening i can walk properly and feel minimal pain but in the morning when i get up there is lot of pain and i cannot walk have to take suppot. can you suggest what is the problem. my right leg is not twisted nor i met with acceident, the swelling and pain has accoured suddenly.