My 5yo has developed a blister 1cm in diameter on the back of her leg which she says is painful, started off as what looked like small spots clustered together but over night has become full of fluid and almost ready to pop, she has a few more of these little spots elsewhere on her body. She's already had chicken pox so didn't think it could be pox again. She also suffers with eczema but it's not due to that. Anyone have any ideas what it could be?