What is this lump?

It feels like a nipple but its red instead. Its on his front shoulder. It looks like it could be filled with blood? Been there a while but since I bathed him today I got a good enough look at it to grab these pics. 





Trying to stay away from the vet unless it gets really big. 

It could be a cat bite if this cat goes out.  They often turn into an abcess which does need treatment.  

Gosh, it's really hard to say.  The surrounding area doesn't look inflamed...is he sensitive to the touch there?  How long has it been there?  Is it possible he's always had it?  I'm wondering if it's possible that it's a mole or wart?  Could you send a picture to your Vet and ask them if you should bring him in.  Obviously you should take him in if he is sensitive to the touch, because an abcess would be bad news.

lol if I sent a picture to my vet for even a pimple he would tell me to bring him in. Vets here will NOT give you ANY over the phone advice. Its always "We need to do an exam". I did pop it last night (I know, shouldnt of) and now its a teeny lump with a scab. Bloody looking clear fluid came out. I will keep an eye on it. He doesnt go outside nor do I have other cats for him to fight with. Its possibly hes always had it but ive never noticed it.