Am I ok or is something wrong??! Please help me!!?

This has been happening for the last week . Every time I masturbate I start to bleed. I'm not a virgin and it doesn't happen when I have sex only when I masturbate . It's not a lot of blood just a little but I don't know why it's happening..? I don't have long enough nails to were I would get cut and I already had my monthly  .. So I don't know what's going on can you please help me ?? I'm really freaking out !