Hello,
This looks like trauma during masturbation. Doing masturbation with a toy hammer and that
too in a rough manner can lead to tears or injuries to vagina or cervix(if there was deep penetration).
Just take some rest and use sanitary napkins to absorb bleeding. Please do not use aspirin as it will aggravate bleeding. You can use some mild analgesics and antiinflammatories. Till there is complete healing, abstain from masturbating.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care.
Don't worry; you probably just irritated your cervix or scratched the skin of your vagina wall. No biggie as long as the handle of the hammer was clean; I hope you washed the hammer really well before commencing (and then, of course, washed it afterward before you putting it back in the toy box). It's possible to get a bit of bleeding from the cervix at certain times in your cycle from being bonked by something as cushioned as a penis, let alone a hard toy. Possibly a good idea for future use is to buy a massager at the drugstore (they are sold with a dulcet-looking photo of someone holding the massager against their neck). They work fine without penetration.