I may or may not have staph infection but it's getting better on its own. What happens if untreated?

I am a marine and I just got done training for three days with no change of clothes and no shower. When I got undressed to take a shower I say I had this small red bump that kind of looked like a pimple on the right side of my thigh but instead of being white on the tip it was black. I squeezed it to pop it and some gooey clear stuff and blood came out but no pimple. I cleaned the area very good and put Neosporin on it and it is going away. What happens if its staph and I don't seek medical attention because it's getting better on it's own?