meh, you just worry too much.. and it'll only really go away with time... i used to be like that.. and i still get that way when i'm smoking at my mom's house. cuz if she catches me it just might be the last thing i do.... but yeah.. just sit back and relax.. play games or something to keep yourself distracted until you can do whatever without experiencing the paranioa...

and if you find yourself in a fit, lay back on your bed with your arms above your head (it helps 'open' the lungs a bit more) and just take deep breaths til it subsides... and this is the hard part, stop focusing on your heart rate lol... i find when i'm having an anxiety attack (i have anxiety problems even without weed) if i focus or even pay attention to my heart rate it makes it worse/last longer..