This sounds like severe allergy. Have you taken any new medication that could have caused this? You mention using a liquid soap, so it seems likely that has caused this, but it seems more like a new medication could be the culprit. I had experienced severe itching when I took Cefixime, and since then steer clear of this antibiotic.
It looks like the oral corticosteroid and antihistamine should take care of the allergic reactions and shouldn;t take more than a few days to clear up. Wish you the best!