I did the same with my middle daughter in 1st grade. She would get into these upset crying episodes in the late morning, and they wanted to drug her to calm her down. Later on, as I was able to more closely observe her at home, I discovered that she was hypoglycemic (my wife's side runs to diabetes and hypoglycemia), her episodes were due to low blood sugar, and the fix was to just make sure she had a high-protein breakfast