Hi there, I'm Dr. Sara! I apologize that I'm not set up to take phone calls, but I'd be happy to give you my thoughts on Tofu.
Our pets can get scabs and scratches from traumatic injuries of all sorts - and most of the time we have no idea how they did it. Sometimes they can also develop little skin masses that can bleed or scab over and look ugly.
In general, for small traumas, we expect it to heal with little intervention in a week or two. A lump or mass that is bleeding may not heal up on its own. Sometimes it's a benign "wart" type of mass but if it keeps bleeding and bothering him, then it should be checked out by a vet.
With small wounds I suggest clipping as much of the fur away as possible and keeping the area clean and dry. Peroxide can be irritating and delay the healing process, so warm water would be a little better. If it's bothering her quite a lot, getting larger, or showing signs of infection like swelling, excessive pain or redness, or discharge, she should be examined by a vet. Likewise if it's not showing any signs of healing after a few days, it might need to be examined.
Please keep in mind that I'm making an educated guess based on your description and my education and experience - nothing can replace an in-person exam by a vet.
I sure hope this info is helpful - Please let me know if I can answer any other specific questions for you!