What do you do if your cat has lumps under her nipples and open wounds on the skin?

Take it to the veterinarian. Normally the vet will prescribe an antibiotic ointment to avoid infection.

More likely than not, it is nothing. It could be a clumb of muscle or a fat deposit, or a calcium deposit. These are common, and should be pretty small. (like the size of a pea or a penny) There is...

Well, raccoons get this lump, called a debrah when it is kept in captivity. If you love it, you will set it free and the lump will go away.

These are systs , your vet should check these out in case they are malignant or benign

I'm not sure about that, but in my opinion I think you should go get it checked out by your family doctor. It's better safe than sorry :) if you are going through pubery it is perfectly normal