A couple of years ago ... when I traveled to Europe ... I had something similar ... not sure if hers itch ... but I got these itchy hives everywhere ... the dr said it was a reaction to something I ate ( even tho I didn’t eat anything different than what I ate at home) he had given me a shot of something similar to aBenadryl shot and some pills for allergic reactions ... it cleared it up surprisingly .... he said it was an allergy to something I was having that I must have developed more recently .

Not sure that’s what it is obviously .... but try allergy medicine it might just take care of the symptoms at least for now until you figure it out.