Ooh, interesting. And yes, that's what I was seeing too--that it could be from something non-obvious because it was over time (or, as you say, a while ago). Sounds like a reasonable theory, and I hope you're right!
Glad to hear the cream seems to be making a difference in the meantime...
Interesting theories! Glad the cream is helping.
seems like a reasonable explanation regarding the body wash. My DS is super sensitive to soaps/washes etc. Anything with any kind of perfume is a major issue for us. I use non-scented everything in my house because of it.