canker sores (aphthous ulcers) occur on the inside of the mouth on the tongue on the inside of the lips and even the posterior pharynx (back of the throat). less commonly aphthous ulcers can even occur on the penis. there can be other innocent mouth lesions like inclusion cysts (looks like little water-filled pimples) but you would need to see his medical provider so this can be properly diagnosed. herpes simplex (fever blisters cold sores) do not have to occur from sexual contact. you can pick up the common herpetic virus just about anywhere and from anyone. an innocent kiss a shared glass or a water fountain.
even though canker sores are most common inside the mouth do they occur on the lip? . my 6 yr. old son just got over a cold. he had a moderate temp (102. 5 f) & vomitted a few times. doc said rest fluids & tylenol/motrin for the fever as needed. however he has a whitish bump on his lower lip. while it looks like a canker sore i'm not sure since it is not on the inside of his mouth. he doesn't have any risk factors for a cold sore; no exposure to anyone w/ cold sores no close contact or sharing of anything that could transmit the virus and he is obviously not sexually active.