How can Cymbalta csuse swelling of the legs and feet?

I started taking Cymbalta two weeks ago and on about day three I noticed that every morning I have big, black, puffy bags under my eyes. I could chalk it up to the lack of sleep I'm experiencing, which is a side effect of the Cymbalta, but I think it's more than lack of sleep. I think it's an additional side effect. I've lost sleep many many nights when I was not taking Cymbalta and NEVER had these big, black bags. I've heard it can cause fluid retention, so...