What Causes Swelling In The Vagina?

I am 21 and im 5’9 and not sure of my weight around 300 pounds I would say. I’ve never had any health problems before expect for the expected cold and I have chronic bronchitis. I went to the bath room earlier and found that my vagina is very dry epically after just going to the bath room. So I just put it out of my mind, then when I went to lay down I noticed that it feels really full like there is a lot of pressure also it feels like my vagina whole not sure of the medical term ( were the pee pee goes) is like swollen shut, this is freaking me out because I haven’t had sex or done anything to cause this also I have been having really bad lower back pains and cramps in my side