a few times in my life (4 or 5) i have had a cold sore on my lip. the last time my cold sore had gone and i spent the weekend with my boyfriend. since then i have had no cold sores however, every time we spend time together (last 3 times) he ends up with a core sore type sore on his lip a day or so later and it seems to be a bit more than a co incidence. when we are together we do have an active sex life in all departments (if you no wot i mean). i have had no symtoms anywhere other than my lip ever.
could anyone help or advise wot this could be and a cure/ treatment. the cold sores on his lip only last a day or so before they go completely with cold sore cream from over the counter.
many thanks in advance.

Could be oral herpes.Get tested.Take care.