K.M.
Hi, S.:
Two quick thoughts: I, too, have had itchy skin after I lie down for a few minutes switched from soap to shower gel because it was drying out my skin. Does lotion help at all? Also, a little out there, but itchy skin, especially a back, is sign of allergies. Maybe not the juice (or maybe so?), but perhaps a "general" reaction to spring or something you came across on vacation.
Hope he can get some relief.