My 6mo twin DD's are EBF and just started rice cereal on the first. Everything has been going fine except this morning one of them had a diaper rash (lots of redness around her anus). I read this as one of the signs of an allergy. BUT I did just buy a different brand diaper yesterday (which they have used randomly before w/no issues). Do you think its the cereal or the diaper? Im ready to start...