We're not absolutely sure, but it appears that our daughter might be allergic to latex. My grandmother was highly allergic to latex so it would make sense. The first thing we noticed with DD was that she broke out in a terrible flaky red rash all across her bottom when eating apples daily and drinking diluted apple juice. Once we removed apple juice and apples (we went to pear juice) he rash healed immediately. After doing some reading we discovered that the composition of protein in apples is almost identical to the chemical make-up of latex so the body sometimes thinks you're ingesting latex. She's never been tested, so I can't say with confidence that's what it is. But it is suspect since she had a grandmother who is highly allergic to it.
Let us know what you find out...