First time

Sooo I had sex for the first time last weekend and I made the mistake of not going to the bathroom afterwards and I ddI that same thing the next night and now I’m diagnosed with a severe kidney infection. I know that you’re supposed to go pee after you have sex but I’ve never heard about someone who got a kidney infection from it. Could this be the cause of it? Because I had a UTI at first and I was taking meds for it but I went to the doctor today and they told me I had a raging kidney infection and they almost hospitalized me.