There are many kinds of bacteria which can live in the human mouth; if this condition becomes too severe it qualifies as "trench mouth" (as it was dubbed during WW I, when soldiers often found it...
Possibliities include herpes simplex, coxsackie virus, hand and mouth disease. All of these are pretty common, not grave, are contagious, and will go away in a short period of time.
Without knowing exactly what you are referring to as bumps, i.e. size, You may have Thrush. A yeast infection in the mouth. Usually you can help get rid of it by cutting sugars and simple starches...