What about prior to that. Think hard. Any exposure to plants.
Also, any new detergents, foods, perfume or medicine?
Okay. I suspect this is either an allergic response to something (quite obvious I know) or something called pityriasis rosea.
PR is a herpes virus that causes symptoms just like this out of nowhere and causes itching.
Treatment is just as you are doing.
The only way to tell for sure is to see your doc but I think you are taking the appropriate measures at home.