Herpes presents in a number of ways beyond what people consider "typical."
However, if your bump started with symptoms before your sexual encounter, then it could not have been caused by that sexual encouter.
Hi, of course only testing would confirm, but since that area was irritated before you had sex it would not be related to the act and it does not appear as a herpes sore as they are not puss filled. Seems like a simple pimple.
With herpes sores, its most often starts with one clear sore that opens and spreads the virus to the immediate surrounding area in a cluster type formation.