Our red eared slider turtle question

by Cami
(Las Vegas)

Our turtle had a bloody membrane coming out from under it's tail. What could this be? When I first saw it yesterday and thought, if I didn't know better I would think this turtle was giving birth... Which I know is not possible but it's the best way to describe what it looked like yesterday. Today it's a little longer and it is bloody. I wondered if it could be it's intestines coming out or some sort of tumor. I even wondered if it had gotten it's tail bitten off but it kind of looks like it is holding it to the side. Looks painful. What can I do? I don't have a picture of it do I need to take one?