No idea how to explain this but my hamster looks like she is sick.. is she sick?

Okay so back in December of 2010 I got a hamster, a boy and so I decided that we should get him a friend because as some people say that hamsters are loners I think that they are just like humans and if they put a human next to you, after being kept in a room (cage) for so long and then you find a friend there so I got a female hamster for the male so they can.....uh you know. Anyways the most important thing is that I was looking at my hamsters and i noticed that the girl (I cant tell then apart because she is lighter and bigger) kept lifting her foot up so I saw a red thing and I picked her up to check what it was and all her belly looked like it was bleeding.I have seen this for three days and I'm really worried about her and i don't know if she is pregnant or not but I just hope shes felling okay. She still runes on her wheel and she drinks a lot and eats normally but seems more aggressive and does not want to be held. PLEASE HELP ME! IM SO SAD AND I DON'T KNOW WHAT TO DO!