What could cause this rash on face?

My daughter is 15. She went for a power walk Monday morning along a nature trail. When she got back to the car about an hour later, she began to break out with a rash on one side of her face. Through out the day, the rash increased and eventually spread across her entire face, including her forehead. She complained of her face feeling tight. By time she showed up at my work, around 4pm, she said it felt like her tongue was getting too big for her mouth. It didn't look swollen, but she was talking a little funny. I immediately gave her some benedryl. An hour or so later, she said her tongue was back to normal, but the rash was still present. This rash is a very fine, pinpoint sized raised bumpy rash and although each tiny bump is not red, her whole face is. Her doctor said to just keep giving her benedryl every 4 hours. If she wakes up with it tomorrow morning, I'm supposed to take her back. Now it looks like it might be spreading to the backs of her arms and knees.

What could cause this rash on face?
She obviously got into something on the nature walk. If the rash is spreading take her to the docs and get it checked out, Also get her scheduled to see an allergist to get tested so you find out what she is allergic to. The allergist will write her out a script for an epi pen to use if she has another allergic reaction.
Reply:If the atarax doesn't work well use something else. I was taught by a famous gerentologist that Atarax is not effective to control itching. Report It

Reply:She may have gotten into some poision ivy. Does the rash itch? Is her tongue still swelling? Sounds like she needs to get back to the dr.