Pain down there

Okay so most times I have my period down there becomes quite dry and it really hurts to touch, to pee and to have sex, and at its worse it hurts to move. I dont know why this happens. But sex makes it worse. I have a feeling its the pad I use (always infinity night) but ive used that for years. It was only when I became sexually active when it started to occur. I feel like the lips become very swollen and the area is read. It takes a while to become better and i use vaseline to deal with the pain. It also feels like I have bumps sometimes but I dont think it will be an sti because I have only been sexually active with one person whos only sexual partner is me. Can any one help or relate?