vaginapagina | open sore in labia

So I get pimples on my inner labia every so often--usually no big deal. I had one for a couple weeks or so, and as usual it was a bit itchy and sore, but I just tried to leave it alone and more or less forgot about it!

However, yesterday, I got back from a camping trip and took a shower and realized that it had turned into a really large, pus-filled, dark-red-purple-almost-black lump. It was very swollen but not too painful to touch. I squeezed it and a lot of blood and a smaller amount of clear pus came out. Once I squeezed most of the stuff out I washed the spot with a little antibacterial soap, put on some comfy pants and tried not to stress about it.

Today it's no longer a purple pus-filled swollen lump, but is pretty much an open sore. It's not very big but it's a bit painful. It looks kind of like a tiny burn, or your skin when you pick a scab off. Other than that it seems kind of normal...no bleeding, no more pus, not really swollen. I guess my question now is -- would it be safe to put some bacitracin on it to avoid it getting all pus-filled again?

I suspect that while it was swollen initially, I scratched it a bit too much by accident with a fingernail, or maybe even nicked it a bit while shaving, and so there was a cut on it. Then I think that probably going camping, not showering for 2 days, swimming in a lake, sweating, etc. all contributed to it turning into a big purple lump. Does that sound plausible? If it doesn't get better in a couple days I'll go to the doctor but if it's just a minor thing that I could treat at home I'd rather just do that. I've been tested for STDs fairly recently (March) and my partner and I don't have any other partners so I don't think it's any sort of sexually transmitted infection.

Thanks for any help anyone can provide!