I’m 16 and I’m going through pain, it’s right at the top of my crack and send me a agonising pain  around the area and hurts a lot more when pressure is added and when I sit down, bend my legs in bed and when I’m lying down, my mum thinks it might have something to do with sciatica as I’ve had pains in the back of my knees not less than 6 months ago, what can I do ?