Help with my anxiety and exams?

I'm more than just a little stressed about my exams. I've been hurting myself & i constantly feel like i'm tired even though i've been sleeping 8-9 hours of sleep a night. My mom took me to the doctor and he said that he thinks i have an anxiety disorder (becuase of previous situations of my life and stuff). I worry about everything but this time i really really cant do my exams and i mean it. Everytime i think about them i want to shut down and cry. My doctor thinks i'm ok to still write them but i cant do it. i just cant. i really need help. he told me i should see a counsellor but i can't get one until after my exams. my exams are next week. please help me because i dont know what to do. i feel like my head is pounding and i just want to run away from all this :( I wanted to tell my doctor im not ok when i saw him the other day but i couldnt do it.. im 17 btw and i know this sounds stupid, but i really can't do this anymore, i cant cope with my exams, i just cant do it.