I need help.

I've been have really bad pain in my vaginal canal for a while it comes and goes its very random but hurts really bad and sharp pains. My std tests keep coming back negative and so do the pregnancy tests and ultrasounds. My doctor wont send me for a pap smear cause I'm too young even tho I've been sexually active for 3 years now and I'm turning 20. He also wont send me for other tests or for an obgyn. It hurts and he doesn't understand that it feels like someone is stabbing me in the canal he thinks I'm talking about my uterus and my stomach no matter how many times I explain that its the canal like where the tampon goes. Does anyone know what could be causing it? I have no clue and neither does my doctor