I have a weird pain and need some help please

Ok so I'm on my period and I've been getting a weird pain down below I'm not sure what it is but it's painful to do anything during the day even doing nothing. It's not exactly a burning feeling it's just uncomfortable and it feels very very dry. I had sex today and I started bleeding more even tho my period was basically gone. I'm only 15 and not so sure what is happening exactly with my body right now but I would appreciate some help.