Sexually transmitted disease. Mega panic?

Hello dear community,

I (male) had sex with a woman 4 months ago. It was a summer evening and we went swimming naked in the lake. Afterwards we had sex on the lounger. It was a one-time thing. After about a week I felt a burning sensation when urinating. I went straight to a urologist and explained the situation to the doctor. He prescribed me antibiotics for 20 days. I took them and everything was fine while I was taking them. In the meantime I contacted the woman and asked if she was okay and she had nothing. Then I went on vacation for two weeks and the burning came back as well as pain in the pelvic area below my stomach, so I went back to the doctor and he prescribed me antibiotics again for 50 days and did an ultrasound of my pelvic area, my stomach and my bottom. His statement after the check-up was: You drank too much water and I can't see anything and it was really uncomfortable in my anus so I couldn't relax, I think it's normal when someone is fiddling around with your hole, then he said it doesn't make sense and prescribed me some prostate tablets, which I only took for one day and then stopped taking straight away because the side effects were too severe. But the doctor also said that if the side effects occur I should stop taking them. The 50 days are now up and I no longer have the burning sensation but I have a strange feeling in the pelvic area under my breast, as if someone was pressing on it.

I've had problems with urinating in the past. But that was years ago and back then I went to see a different urologist who checked me. Back then he stuck something like a rod into my genital area and the pain is unbearable and I don't want to do it again and I think about it every day and I'm just scared. I really don't want to cry like a child but it was really bad. So my question to you: is there another way to get tested? I've been really desperate for months and can't talk to anyone about it. And I keep thinking I have some kind of illness and I'm panicking. I'm hoping for help.

Lg