Social anxiety question???!?!?!?!??!!?

Im a 15 year old guy and i have got really bad anxiety. Whenever Im in school emblies or when im sat in front of the cl my face goes all red, i sweat a lot and i feel like everyone is concentratin on me and takin the pi$$, my face or my neck starts twitching sometimes and im convinced other people can notice.. Im startin skool tommorow after 8 weeks and am feelin really nervous. Im gettin stomach aches and head aches just thinking about it. We've got all these new teachers starting and im convinced one of them is going to shout and embarr me in front of everyone. I dont even know if we've got an embly tommorw but if we have im gonna have to go to it and im going to be a nervous wreck. Itz going to be really hard for me to go asleep today as im goin to be nervous about skool and ill be suprised if i even get an hour of sleep. Anyway my doctor prescibed me lorazepam 1mg to help me go to sleep at night, and advised me to take 2 or 3 when ever i felt i couldnt go asleep. i had to go to a party about a week ago and was really anxious as normal so i took 1mg of my lorazepam before i went and i felt alot better than usual even though i got nervous occasionally. So im thinking i should take 2mgs or even 3mg of lorazepam before i go to skool to make me feel better. How would this make me feel and will it work for me?