Thick White Discharge With Smell Of Vinegar, No Itching, Lower Back Ache, Fever After Unprotected Sex. What Is The Cause?

Hello, I recently had unprotected sex.. we usually use condoms but we did it without.. i told him to pull out after 15 seconds because i was DEFINETLEY not sure about having sex without once (since im not on the pill either) the man i had sex with is my partner and has gone for a check up to make sure everything is Ok since he has had sex before and i have not before him. It s the day after we ve had unprotected sex and he didn t ejaculate inside me since it was only 15 seconds but my discharge has changed to a thick white sticky texture and smells like vinegar?!! I m not itchy anywhere but my lower back ache s alot.. What is this?? I ve had water infections before in my last relationship and i guess are prone to them because of poor nutrition but I don t know what this is. Those are the only symptoms i ve had except for having a normal cold and temperature. What could this be?