Welcome to the forum.
Bottom line: I doubt you caught an STD or infected your gf with anything.
FYI, there's never a need on this forum to ask for "no judgement"! We'll sometimes tell people that what they did was pretty dumb, but it's a point of pride that you won't find moral judgments on this forum.
You describe a partner who is unlikely to have any STD, based both on her sexual history and her personal confidence about it. Second, the antibiotics probably would have prevented some of the most likely STDs that might cause symptoms like your girlfriend's. That said, I probably could reassure you more if you will say what drug(s) you were given. "1mg antibiotics" makes no sense.
And STDs are unlikely causes of symptoms like your girlfriend's, which sound typical for a vaginal yeast infection. Gonorrhea or chlamydia don't cuase sore, irritated labia. If your gf has previously had yeast and the symptoms are the same this time, it's very likely that's what she has now.
The only potential issue is herpes. It can be common even in women at generally low risk for STD, so perhaps your new partner had it; is not affected by antibiotics; and the early symptoms could be redness and swelling for a day or two before blisters or sores appear. Also, I assume you haven't had any penile sores or irritation that could suggest herpes, or cold sores on or near your mouth.
Say nothing to your girlfriend about your other sexual exposure. If your gf's symptoms are severe or not typical for yeast, or if they continue moe than a few days, encourage her to see her doctor for diagnosis. If herpes or other STD shows up, deal with it then. However, I stress that I think this is very unlikely. It's probably just yeast and has nothing to do with your other sexual contact.
I hope this has helped. Best wishes-- HHH, MD
Thanks so much...very appreciated.
My opinion hasn't changed -- unlikely to be an STD, but I can't rule out the possibility of herpes. (I would say under 10 percent chance of that.) Other STDs, like trichomonas, gonorrhea, or chlamydia, are even less likely. But if her symptoms persist despite yeast treatment, she needs to be professionally examined to know for sure.
thanks....I will. It is OTC counter I believe perhaps a combination. One last question, with the updated information above do you still doubt I passed any of the above STD's and is non-std related?
Trichomonas is not a likely cause of your partner's symptoms. Is she treating herself with an over-the-counter yeast medication? Some yeast infections are resistant to the usual anti-yeast treatments. If her symptoms are no better in the next day or two, she should not try other OTC treatments but should see her doctor or clinic for professional evaluation.
Just an update as well...my g/f is worried that she is on day 2/3 of yeast treatment and she hasn't seen relief and worried it could be something else...almost like she is about to ask me. She maintains she is red and painful, itchy with now a minor "fishy" odour. Still no pain on urination or other discharge. Im not sure if "trich" above would cause such a thing, if the first girl even has it or again if Im over thinking this. I guess that's also one that cant be explained non-sexually..except in rare cases. Monday cant come fast enough to get the other partners results assuming she is honest ....big big lesson learned.
Your a good doc...thank you. Just to reference your question I was prescribed Azithromycin 250mg...took 4 in the office and 2 per day for the next 2 days. Im assuming the other girl is being honest but Im assuming being responsible enough having an IUD and knowing the factors around it she would be. Appeared very health conscious and in touch with her body. She did confirm they test annually for woman with IUD and can only assume that means STD's as well. I was told the other risk can be "trich" but again Im assuming she has been tested for that and I have been test free and monogamous 7 years with this current girl. She is on day 2 of yeast infection treatment. I just found it a scary coincidence 7 days after I sleep with her (10 days from when I slept with the other girl) she now develops these symptoms. Someone said most STD's wouldn't culture that fast especially with woman. No sores of any sort up or down on previous girl or me. Again thank you for your honest straightforward information in advance