Major allergic skin reaction - advice please?

[EightToSixer]

We went to the cinema this afternoon and DD (10) started saying she was itchy. I checked her torso afterwards and she was covered in huge blisters. Took her to GP who prescribed antihistamine but it got worse and worse so I ended up taking her to A&E as she was covered in bright red wheals/hives and started to feel sick and dizzy. While we were waiting she said she couldn't see and fainted. The gave her steroids and more antihistamine and once rash started fading slightly sent us home.
I've racked my brains to see if she has eaten anything different, she hasn't. We haven't used any different cleaning things of any type etc.

Does anyone have any experience of this extreme a reaction? Did it happen again? What do you suggest? Should I seek an allergy referral or is it a one-off.

Any advice great fully received, it was just so severe it frightened me so much.

Might be worth posting in 'Allergies' as there is lots of fab advice about this sort of issue. Some very experienced posters there.

My DH had a bad allergic reaction once, started out as a small swollen patch on forehead, ended up in A&E with his entire face swollen ( he looked like Neanderthal man!). He hadn't come into contact with anything new. He was referred to an allergy specialist and they did a few allergy tests which didn't show anything. He was diagnosed with chronic urticaria, it's when your body has an extreme allergic reaction. Just because he reacted to the allergen this way once does not mean he will necessarily react the same way again. That was over 5 years ago and he's never had a bad reaction like that since.
Not really advice, just wanted to reassure you that it could be a one off, but no harm in getting a specialists opinion.

Green cyber. Thank you, I hadn't found that board, will post over there too
Cheese monkey - that's reassuring thank you :)

I remember this happening to me once when I was a child, mother racked her brains for what it could be but it never happened again so we never found out. Hope your DD is the same.