Urtecaria with a fever??? What could've caused it?

[Toothache]

I noticed on Friday at about 4pm that my ds (3) had a big raised red lump on one of his buttocks. It was about 2inches in diameter. It looked like Urtecaria (which I suffer from due to a tomato allergy), but it wasn't bothering him so I left it. By 6pm there were more huge circles appearing over his back, then onto one shoulder. I gave him Piriton and phoned NHS24. They asked all about what he had eaten. That day he ate:

Cornflakes,
Cheese sandwich on wholemeal bread
Macaroni cheese
Salt n shake crisp (without the salt)

They just told me to keep giving him Piriton. About 2 hrs after that he developed a high fever! I took him to the out of hours Docs..... again it was just Piriton and Calpol and off home.

An hour after that his lips began swelling, but I was told as long as his breathing was fine then not to worry.

This is now Sunday and I'm still having to give him Piriton and Calpol. The reaction is still happening although its moved to his arms and legs now and he's developed diarrhea too!

Has anyone heard of an allergy that causes Urtecaria, fever and diarrhea?? Could it get much worse?

I have a few allergies and also Asthma, I feel so guilty that he seems to have inherited this from me.

Meant to ask also if I should insist on blood tests to find out which food he may be allergic to? Poor wee mite.

Toothache - did he have juice at all?

My DD had this kind of reaction to an orange ice lolly - think it was one of the additives that did it. She was very poorly for about 4-5days after the initial onset of the urticaria.

sounds silly but is he allergic to an ingredient in calpol?

Kiddies ofetn get urticaria triggered by an infection so if it's a virus causing his fever & diarrhoea it may also have caused the urticaria.

Thanks guys. Soapbox - he just had his usual apple juice.

Jampot - nope not Calpol, he started on Calpol about 4 hrs after the original onset of Urtecaria.

Nik72 - Interesting, I wondered if it could've been triggered by something other than an allergy!

However, I think we;ve cracked it! The HV gave me a freebie pack with toothbrush and toothpaste. It's the 1st time he's had adult toothpaste and we used it twice. Both times the Urtecaria and fever flared up within 2 hours! Used his kids toothpaste tonight and all is well.

Could it be that? Has anyone heard of an allergy to TOOTHPASTE?

How ironic considering my posting name!