Why is the thing next to my clitoris swollen?!?

I'm on antibiotics because of a UTI. I am eating yoghurt but still my vagina area has been quite itchy. This morning I went to the bathroom and washed 'myself' and i noticed the thing next to my clitoris is swollen! I do have some canasten cream but is it going to help? PLEASE HELP ME! ps: I'm 15 and I'm not sexually active