I am a bit like Fiona in that I held off giving DD cows milk for a few months. Toddler formula and milk is high in sugar so I just kept her on the normal formula she had been on and slowly increased the amount of cows milk she was having and by the time she was around 16 mths she was on it full time. If you think it is related just put her back on what she was on and if it keeps going it might be something else but at least her system isn't having to deal with both at once. She will be perfectly fine to keep having the formula she has been on for a few more months. xoxox