It sounds like you have had a genital HSV-1 outbreak, let me know if I got this wrong.
HSV-1 is really common; in Canada we find most adults have it. Most people who have HSV are also unaware that it is there because they have not had symptoms. The easiest time to pass HSV to another person is when someone is having an outbreak, but HSV can still be passed when a person is not having an outbreak since the virus will shed from time to time. This means it’s possible for someone to have HSV and pass it to someone else without them ever knowing they had it.
It’s possible your boyfriend could have had this on his genitals and not known about it, or not recognised the symptoms as they did not happen often or were mild. It’s also possible you could have HSV from a previous partner and are only getting your first outbreak now. It’s difficult to know if that “rash” was an outbreak or if it was just a wound from a zipper. The only way to tell would be if a test was done on the wound on the penis.
As HSV-1 has evolved to be around the mouth area, we find that when HSV-1 is on the genitals it does not outbreak or shed as much when compared to HSV-1 on the mouth or HSV-2 on the genitals. Given this we think the majority of HSV-1 is passed to someone’s genitals when they receive oral sex from a partner who has HSV-1 (cold sores) around the mouth.
As you can see there are a few different possibilities. I think the most likely situation is that your boyfriend is unaware of HSV-1 being around the mouth and passed it to you with oral sex. To explore your situation further I would ask your boyfriend to have any suspicious wound on their penis checked by a health professional if you think it could be HSV. There are also blood tests for HSV which may give you some additional information. HSV can take up to 3-4 months to show up in a blood test. As it has only been 3 weeks there is a chance your blood test could still be negative if this was just passed to you. A positive swab test and negative blood test means this just happened. If your boyfriend gets no HSV symptoms they could always do a blood test as well if they were wondering.
It can be difficult to know for sure how HSV was passed to you since HSV is so common, most people do not have symptoms and you can get your first outbreak at a later date.
Also have a look at our HSV page for additional information.
Let us know if we did not answer your question or if you have any further questions or concerns.