If you are in the U.S., your doctor can't tell your mother what you tell him. Just tell her that you think you have a bladder infection or a kidney infection or something, and that you need a doctor appointment. Then when you get there, tell her you want to handle it by yourself. If you are mature enough (you say) to have sex, then you are mature enough to tell your mother you want to go in to talk to the doctor and have the exam privately. She won't fight you about it right there in the waiting room. (Or, if she does, call Security.) Don't self-medicate, get to the doctor.
It's great you used a condom but unfortunately you can still get herpes and/or genital warts from having sex because those are spread by skin to skin contact. Man, it would be such a huge tragedy to get either herpes or warts at 13. You are going to have to see the doctor cause there's no way around it. If you feel you're old enough to have sex then you need to also be ready and willing to accept the possible consequences (for example std's and pregnancy) and handle any issues that come up by going to the doctor. You can't be embarrassed about this because it's necessary to get checked out so you can get proper treatment.
I did not yell at you, I just made a simple comment about sex at a young age.
You're the only one that hasn't yelled at me for having sex at a young age, so thank you!
nooooo peroxide girl that will hurt like crape dont put that on or near your vagina
While condom use is a good thing, it is by no means a guarantee against all stds. Herpes, for instance can be transmitted even with condom if the sores are near the base of the penis. This is why you don't want to be having sex at your age. There is still a lot you need to learn. Talk to your mom. See a doctor.
You should see a Dr, but at age 13 you should not be having sex.