Questions concerns and advice.

Back in june I started seeing this girl who I met at a bar. Ended up having sex with her and becoming pretty good friends with her. We both agree that we wouldn't make a good couple because she's older then me and we don't have a lot in common. We are just monogamous sex partners. If she want's to go out and see other people that's fine and the same with me. As long as we are honest about it and we don't hide anything. Then in september around the 7th or so I got a sore on my penis. I initially thought it was from self-gratification which I do a lot and if I don't use lube I usually get a sore on my right side. This sore was on the left. I kept it to myself and it went a way after a few days didn't think nothing else of it. Then last night I was on the internet and I starting looking at herpes websites and I seen a pic that looked similar to the sore that I had. It was a long time ago and I don't remember exactly what it looked like just similar. I know I need to get it checked but I can't do nothing today because today is sunday but I will in a few days. Honestly I'm quite I wouldn't say scared but I really just want to say some four letter words because this is another inconvenience in my life I don't need. My questions is should I text the girl and tell her about my sore and see what she says, or should I wait and see what happens with my test. My mom told me not to say nothing yet, I don't know why. If she has it she doesn't know about it. She's recently divorced and has had one boyfriend since her divorce (I know that don't matter). And as for me before her I didn't have sex for around 6 years. I know if she got tested her results would probably yield better results because if she does have it she would have had it longer and my antibodies are still forming. Any advice.