STD OR UTI?

So I slept with the guy I’ve been talking to for the first time a few days a go and he finished inside me. Now i have pain while urinating, discharge and vagina discomfort (itchiness) already went to the doctors and got antibiotics for it. She said it was a UTI and I’m getting tested for STDs but my question is .. can you develop something like that overnight ? All the symptoms started the next day after intercourse, and they are pretty bad.

P.S: I already know all this was stupid of me for even allowing it to happen but I am really concerned about my health and currently in pain because of it so I don’t need negativity nor judgment right now. Pls & thank you