Food allergies in weaning

My baby is 6 months and we started weaning a week ago and he was perfectly fine, but yesterday he had an allergic reaction. We went to A&E, have been prescribed antihistamines and been referred to an allergy clinic but was just wondering if anyone had any similar experience or any advice as to what we do now? The dr says to just keep going but we are a bit wary of doing that! He tried baby porridge, carrot, sweet potato, normal potato, peas, parsnip, pear and pitta bread and all was fine, then yesterday he tried cooked apple and had a tiny bit of a banana then had the reaction. We went to hospital after this. Today we thought we’d go back to basics and give him baby porridge again as he was fine with that, but he reacted the same way, if not worse! We have spoke to a dr again after this who said to just keep trying other things but I think it might be better to have a few days off? Has anyone had reactions to bananas and porridge even when it’s been fine before? Or any advice on other foods to try which he may not react to? I’m just a bit scared of giving him more if he’s now going to react to everything now, whilst we wait to see the allergy specialist?