Swelling in legs. Please help.

My legs are swelled since last one week. The portion from knee to feet is swelled. Whenever I sit on a chair with my legs hanging down my feet swells up more. It goes a little when I walk. The swelling is very prominent and when I press on my skin it even creates dimples showing the evidence of swelling. I had consulted a doctor he just touched my feet and said that it's because of vitamin D deficiency. I have vitamin D3 level 3.5 which is very low but I had never faced any swelling before. Also I am a dancer and dance for almost 13 hours a day it did not create problem for last month and suddenly there is swelling. I am not satisfied with what he said as I am taking supplement for D3 and why will only my feet swell in case of deficiency. Please help.