HELP! swollen labia! what's causing it?!

I decided to go to the bathroom and check out what was going on down there. I look in the mirror and to my surprise, my left labia was swollen!! And when I say swollen, I mean SWOLLEN! It was super fat, it almost looked like it was gonna pop! I got so scared cuz I didn't know what was wrong. I'm too scared to go to a doctor and there's no way I'd ask my mother for help. So I started looking up causes on google. It could be from a yeast infection, which I'm thinking it is..but I want to know if other females have experienced this and what it ended up being. 

So after it was severely swollen, I started a hot bath and dipped half my body in to maybe get rid of some swelling. Didn't really do much. 

Hours later and the swelling is gone. I took Benadryl for the itching and so far so good. 

But please, if anyone's experienced this, PLEASE share cuz I have a feeling it's gonna happen again and I want to know how to treat it!! 

BTW it wasn't necessarily painful, it was more uncomfortable if anything and really sensitive.