My son has itchy toes. Same ones. I sometimes think it looks a little red but have also seen nothing. My ped said he has undetermined dermatitis. We use an over the counter cream which makes it better. Look in that section and give this a try next time she complains of it.
It could also be as stated above athlete's foot. They make powders and creams for that as well. good luck
what material are her shoes made of , I know the plastic outdoor shoes have been known to cause it, also her socks ,if its between her toes it may also be athletes foot ..