Mare with possible hernia?

One of our mares recently came up with what we thought was a cut in her belly button (it was bleeding a little) and now about half an inch lower on her stomach is a section of swollen area. I have been doing some research and its sounding like a hernia. Does it sound like that to you guys? I can get pictures tomorrow. What causes a hernia in a mare?
Thanks

Is she a breeding mare? Pregnant? Foaled before?

Yes an umbilical hernia is possible, some horses have them and they're fine, just a little bump, and they can be left like that and be fine. However, if this is new I'd get it checked. Sometimes the vet can just poke it back in with his finger and it will magically close up on its own. Sometimes it requires further investigation. It is usually caused by a torn muscle and the stomach intestines poke through, or fat layers opening etc etc........actually it's a big subject, I've just realized this is going to take more typing than I'm able to do right now, but definitely get your vet to look at it.

thanks! She is fairly new only had her a few months now and the bump is only like two or three days old. She was bred in the spring but she lost it (not our breeding we bought her that way) and honestly we have had nothing but problems with her