Im 15, and every time I masturbate I bleed and my vagina gets tender.. Uhmm, why..

Uhmm, just a question.
What do you masturbate with?
You might have "POPPED YOU'RE OWN CHERRY"
Or you started you're period.
Hmmm, thats weird who knows....
Sorry, i can't tell you more but, you may need to go to the hospital or the doctors for that hunn.

If this is happening every time, then I would see a gynecologist. It sounds like you have very thin skin in and around your vagina, but I suppose there's a possibility of some growth or cyst or boil that you can't feel that is irritated each time, and it can be treated. It would help if you would describe how you masturbate.

Sounds like you're being too rough.

The vagina is very sensitive. Too much rubbing, or whatever you're doing, especially if you're not lubricated, can cause bleeding. One long fingernail, or rough skin on your hands, or just being too aggressive can cause swelling, bleeding, irritation, and more.

I will have to agree, how are you masturbating? It does sound like it is just too rough, if it is bleeding every time, or you using wrong toys