It is theoretically possible to spread herpes without an active outbreak. However, this is very uncommon. More important, if he's never had herpes before, the incubation period after contact is generally 3-5 days, not 2, and a first attack is likely to be much more severe--swelling, swollen glands, blisters--not just a single small tingling bump. Even if this bump were herpes--I doubt it--it would represent a "recurrent-type" outbreak, which means that he was exposed long before he met you and the outbreak was a coincidence. (Just as when you get a cold sore, you get it regardless of whether you kissed someone lately.)
Blood tests won;t be of value. He'll either take your word for this or he's already made up his mind otherwise, in which case there's not much you can say. If so, that's too bad for him. If he was so sure it was herpes, he should have seen a doctor right away.
Good luck.
Dr. Rockoff