So the past few times I have masturbated everything seemed to be going great. But then I start fingering myself and start bleeding. I keep my nails rather short, so I don't think I'm scratching myself.  I don't have a partner right now, but in the past this didn't happen when he would finger me. It's becoming a bit of a concern,not to mention it's a mess. Anyone else have these problems, or an idea of what's wrong?