I think sometimes when you're reacting, there's so much histamine floating around that you itch from things that wouldn't usually bother you. Last time I had a reaction with hives, I needed to keep taking antihistamines for nearly a week, it takes a while for all that histamine to leave your system. Drink lots of water to help flush it all out. Also, it helps if you take a 24 hour AH & take it before bed so that itching isn't interrupting your sleep.

I would also strip the bed and change all the towels, vacuum everything, in case you've tracked something like pollen inside.

The last time I had hives (on my feet) I got massive relief from soaking them in an Epsom salts footbath. So if you're itching all over I would try a big bath with a cup or so of Epsom salts, give it at least 15 minutes, see if that helps. Otherwise you could just swab each itchy bit with an Epsom solution, leave it to dry. I hope that helps,