My vagina has been itchy for 1 week now. When we have sex it hurts and burns

I only have sex with one person. And he was a virgin. So no way this is STD.. (right? im 100% sure hes a virgin)

My vagina has been itchy for 1 week now. When we have sex it hurts and burns (only had sex once since this happened). And now, theres swollen patches and they are itchy.  (its like a veins popping out or something). I have yellow discharge. I thought this is yeast infection but is it suppose to swell up?

What medicine should I get over the counter. acidophilus pills? or...