Nice visit with my sister... Bill's allergies... etc.|
Today some new part of him was itching so we decided that whatever is bothering him is probably still around.
Some article of clothing or other item with which he makes routine unconsidered contact. I'm hunting a replacement watchband at the moment, for my (not-right-now) everyday working watch, because it has evidently acquired some substance, probably plant- or insect-produced, that I cannot get out of the leather.
If it was an insect toxin on his shirt, for example, and survived the next washing, it could now be on anything else that was in the same washer, dryer, folding stack, drawer...