What Could Red Itchy Blotches On Face And Chest Suggest?

hi I have over the last couple of days started to get red blotches over my face, chest and back that are red and itchy - they look like insect bites but they aren't...I've recently had new carpets fitted and there was a lot of dust from this - could I be having an allergic reaction to this? or is it something else? I've taken some antihistamine but it doesn't seem to be helping.thanks