How could I have caught an std (herpes) if not from sex?

I’m trying to figure out some things while I wait for test results to come back (see my last post for more details). In short the doctor didn’t know if it was an std or just an infection or what std it might be. The red marks are clearing up, but he gave me two medications (one for bacterial infections, one to treat viral infections), and I have been applying polysporin, so I have no idea what is making them clear up.

Anyways, I’m trying to figure out HOW I could have caught an std, herpes specifically. I was tested myself a while back, and since then I’ve only been with a few girls. I have never had any outbreak similar to this in my life. I have contacted each of the girls since this started, and all claim to have been tested shortly before or shortly after having been with me and come back clean. They also all claim to have never had a Herpes outbreak. Also, Herpes first outbreaks apparently come within a few weeks to a month or so after initial exposure… So the girls would have had one by now and know, and it narrows the window down to just my current g/f (whom has never had an outbreak).

The only connection with Herpes I can find, is that my current g/f’s former room mate (of about a year, roughly 6 months ago) had it. But the two never had any kind of sexual contact or anything like that. My g/f is freaking out that maybe she caught it from her room mate somehow (like the whole, getting pregnant by sitting on a toilet with seamen concept). Is something like that possible?

Lets assume for the moment that the girls I’ve been with aren’t lying to me, they’ve all been tested and all came back clean. How else could I have caught it (if in fact it does end up being that)?