After sex, when i went to pee i feel this burning sensation inside my vagina what might it be?

Vaginitis vs UTI: This sounds like a vaginal infection rather than a uti. These two conditions however often run together and it may be best for your doctor to check you for both conditions and treat accordingly.

Skin irritation: Skin irritation is very common after sex, both on the vaginal lips, and inside the vagina. A pelvic exam from an ob/gyn physician would be helpful.