A pimple on the stomach is most likely acne, possibly folliculitis, and possibly boils, and there is also the possibility of impetigo. In this case, it is basically treated by fighting the infection. Since all of these conditions are related to infections, this is where topical anti-infective medications can be used, usually such as fusidic acid cream or mupirocin cream. If there is pus, you can apply topical Longzhu ointment, if the redness is more obvious, you can take oral roxithromycin anti-inflammatory, or oral cephalosporin anti-inflammatory. If the red bump pus is more obvious, you need to go to the hospital to cut and drain the pus.