what is wrong with my vagina

i had sex last night and then when i went to sleep i couldn't even stay asleep bc my vagina and well i'm sorry TMI but right where the dick would go wouldn't stop itching. all day today my whole vagina has been itching and hurting. it even hurts to walk or when i'm just sitting down its painful. idk what may of caused this or if it's even a UTI or what! i've never had a UTI or yeast infection so idk what to look for. i thought it might be bc we used a different condom than normal but i've used that condom brand before and it never effected me like this. idk if it could be an STD but he's the only guy i've messed with so unless he caught something from someone then who knows. i bought the UTI Medicine and took it twice today yet no improvement. idk how long it takes for it to kick in. any ideas on what it is or what i can do to help ease the pain?