Blister under lip. Should we be worried?

This query is about a female age 53 years. She recently had an episode of cold which lasted for 3-5 days. As the cold was improving she developed a group of slightly tender and slightly painful group of small blisters under her left side of lip, which was accompanied by tender left side of face with tenderness in left eye and ear. We thought it could be a side effect to medicine, though she took one tablet of dolo one night when she was feeling a bit feverish, and cheston 2 nights a row , two tablets in total. So we stopped these medicines right away and slowly blisters started improving and now there is a scab left and she is fine. But we read on internet that it could be a cold sore, but she never had any episode of HSV in her 53 years of life and nobody around us has HSV. So should we be worried?