I ate prawns last night. i think i have an allergy. my face has swollen up. what can i do? i'm an actor and i need my face in the next 6-7 hours. help

Do not eat more praw: Avoid that food obviously, and drink a lots of fluids and take some good antihistamin like claritin, (loratadine) and see your doctor.

See your doctor: If you have an acting engagement, a short course of prednisone may be helpful but large dose of antihistamine will likely be more effective. If your problem is indeed from a prawn allergy, on occasions I would also try an injection of epinephrine- but only in an emergency case like having to appear on stage in a few hours.