It could be herpes, though herpes doesn't have a white head on it. It could also be a clogged oil pore (much more likely), a fungal infection, or a host of other things.
Your best bet is to get it checked promptly by a doctor. If they think it's herpes, INSIST that they do a type specific culture or PCR swab on it. Don't let them do a visual diagnosis on it with no testing - that's wrong a lot.
Getting it tested is the only way to know if it's herpes. (It really doesn't sound like it, though.)
Even if you have the same partner for a long time, and your partner has herpes, it doesn't mean that you would automatically get herpes. Some people never transmit it, or might not transmit it for years. It depends on if they get outbreaks, or asymptomatic viral shedding (when virus is present on the skin with no symptoms).
Also, if your partner performs oral sex on you and has oral herpes type 1 (think cold sores), they can give you genital herpes type 1.
Again, it doesn't sound like this is what you have, but I want you to have some basic info before going into the doctor. Because you can have genital herpes type 1 or 2, it's important that they do a type specific test on it, because transmission stats are different (if you and your partner ever break up, or if you had it coming into this relationship and your partner doesn't have it).
Let's not get too far ahead of ourselves though - just go get it checked. If you can, get it checked within 48-72 hours of it appearing. Let us know what happens. :)
Did you ask your partner if he had any symptoms of anything? You definitely need to go to the doctor to find out what’s going on with you. Stop having sex with him until you know what’s going on with you and his status.