bleeding but I don't think it's my period...

Hello,
If someone could give me some sort of advice on what to do that would be absolutely amazing!! 
So I came off my period 10 days ago. I wake up this morning to a pain on the left side of my uterus. I go to the bathroom and watered down  bright red blood kind of spills out... my period isn't due yet and sorry to say but it's usually dark red and mucus like. There is no way I could be pregnant (I'm a virgin). But I'm really terrified and I don't want to go to the ER.