A contact allergy is a allergic skin reaction from contact with a substance that is usually harmless. You usually get a itchy rash that develops over a couple of days, after the skin comes in contact with the substance. The skin first becomes itchy, then red, & swollen with vesicles(blisters). This rash can stay in the area that came in contact with the substance our can spread over the body.
The other reaction is Anaphylaxis. That’s more than likley what happened to WeRNOTAfraid. Also think of anything you might of come in contact with around the same time.
Good luck figuring things out allergies are a strange thing.