She bit the top of your knob Sure it wasn't a mistress you went to see? Anyway, like any cut, it will heal, just give it time and don't pick it. Bit of sudocream wouldn't do any harm. I would however get an STI check just in case, if she's drew blood on you she's done it before.
If you rub some IcyHot on the area it will make it feel better. Or maybe the opposite is true... I forget