S.H.
Since she was 7. And in 2nd grade.
And she was NOT the only one in her class... to have underarm odor.
Per that age.
I get her the Arm & Hammer "Essentials Natural Deodorant." It has NO parabens and no aluminum in it.
Can be found at any drug store or grocery store.
My daughter is now in 3rd grade, and her Teacher, spoke the the class about how some kids are starting to get 'odor' under their arm-pits... and they need to use deodorant, because they are getting older.
The hormones in kids, also fluctuates. Thus, sometimes they may smell and sometimes not.