Hi, I Have Been Having This Problem For About 3-4

Hi, I have been having this problem for about 3-4 months! I l will just be standing there or sitting down, and my legs will get very blotchy and redand sometimes they swell up. I have no clue what is going on but I need to know. Do you know any possible answers, it looks so bad sometimes it looks like my skin Is red and the blotches are purple. It only happens on my legs too..any suggestions?