Could this be Staph Infection?

I lifted up my shirt and right underneath my on my rib cage was a mark with two whiteheads on it I popped the two whiteheads. It didn't hurt, never itched and I didn't know it was there until i actually looked. Now it is a mark with two heads (not white anymore). Could this be a spider bite? My stepson was at my house about 3 weeks ago and he had a staph infection. Could I have caught that from him? I have a doctors appointmetn Friday, but I am nervous because I have two kids at home and don't want them to catch it.