Hi Sunflowers
Poor you and your poor DS. It's a scary experience watching your child have a reaction, so it's no wonder you're feeling frazzled. :(
Can I ask, how long has this reaction lasted? If he is flaring up everyday, then it could well be a viral induced urticaria. Does the rash stay in one place or does it move around, i.e. is it there one minute and not a few minutes later, reappearing either in the same place or in a different area? If you DS hasn't ever had allergies before, and is suddenly allergic, this could be the cause as it can affect anyone and not just people who suffer from allergies.
There are other non-sedating longer lasting anti-histamines that your GP can prescribe, that are very effective for things like hayfever as well as viral urticaria. Piriton is great in an emergency, but it isn't long lasting and you do have to give it for 24 - 48 hours after a reaction to make sure there isn't a repeat reaction after exposure/ingestion of the allergen.
If it's been going on a few days, then it is unlikely to be an allergy, unless he's coming into contact with it all the time.
It's actually difficult to know sometimes which it is, but when you see your GP ask to be referred to a pediatric allergist who will be able to do the necessary tests to check for the main allergens. Until you see the allergist, try and keep a diary of what he is eating and note any reactions, like hives but also delayed reactions like eczema or anything else that's unusual.
I'm not sure if this is helpful, but at the moment you are doing everything you can. Try not to worry, although I need to listen to that advice myself
. I hope your DS is able to go to school for his last week. My DD has loads of allergies and also gets viral urticaria which is a PITA as it looks just like an allergic reaction.
I hope your GP is able to help you tomorrow.
take care.