After much trial and error, my DD (nearly 12) has settled for a Vaseline Intensive Care roll on. I don't want her to use a spray, but none of the 'natural' ones worked, so this is a compromise but she is happy with the performance.
hi CarGirl .. poor dd .. perhaps buy a couple of different types that say they are stronger so she can try them at home before she goes back to school. Either that or have you considered talking to the pharmacist - they may know of something which can help! Some of the men's deodorants may be stronger as well - may be worth considering!