What causes swelling to happen on one side of the body but not the other?

Defiance, Ohio
November 15, 2008 9:32pm CST
I was sitting here and my left side started to feel weird. I noticed I was swelling up in my left leg. I really noticed it in my foot. Than I started look at nmy body and my whole left side from my shoulder down is swelled up. But not my right side. Why would this happen? What would cause this? I am use to my left leg swelling off and on because of problems I have will it after being shot. But what would cause the left side of my body to do this? I was fine earlier today. Do you think it can be an allerigic reaction to something I ate?