My Child Has Bumps, Some Look Like Pimples Inbetween His

My child has bumps, some look like pimples inbetween his butt cheeks. It has gotten worse in the last 24 hours and is very itchy. He also has a major infection in his mouth from a cavity and we have been trying to treat it with antibiotics but I cant get the antibiotics in his body. Is it possible that the infection has spread?