What can I do to stop these panic attacks?

I'm a guy and 16. I have had bad nerves all my life but never this bad. I seem to have panic attacks everyday. It feels like as if my throat is closing up, like as if i'm losing balance and control of myself. I really hate it and its scary like as if i'm going to die right then and now. I try to control them but then my face and forehead start feeling hot and sweaty eventhough i'm not sweating. I have noticed that it happens mostly in really big rooms that the ceiling is at up in or when I have to stand somewhere and stand still cause I like to move alot and it makes it a little better if I get up to move around. It started getting worse when I entered High School and I don't like it at all. It seems to happen in the lunchroom and a few certain classes. I'm kinda Clastrophobic too. I sometimes feel like I have to keep gasping for breath by doing these sniffling noises or I might feel like I have to hold onto something cause I think i'm going to fall over. I really hate but all this only started happening when I entered High School. I never used to have anxiety this bad.