My Daughter (16) Has A Small Sore On Her Lip.

My daughter (16) has a small sore on her lip. It is not a blister, has not broken open, is not painful. She is very anxious about the idea that she may have herpes. She got a swab test today and eventhough the doctor was not at all worried she continues to be anxious. If a sore has not turned into a blister, can it still be herpes? Thanks much, Karin