"Extremely upset" is a little extreme don't you think? Personally I think it is my choice what my kid eats. Would I send her with a candy bar and a Dr Pepper to eat in the middle of practice? No, but chips aren't that bad. Sometimes we have busy lives and if chips or $1.00 for the vending machine is all I have at that moment and my child has to have a snack, then that's okay. A bag of chips aren't going to kill you. A lot of foods that are marketed as healthy are really not any healthier than a snack size bag of chips.
No I don't think so ! It is not just about healthy or not ! I understand your kid has a medical condition, I even know that kind of condition very well. Most people have to take medication though and can't just have a diet. How about just sending little packages of dextroses with her ? That would keep her body going and nobody had to worry about potato chips. And there are studies enough that show the amount of Acrylamid in potato chips is way to high and can cause cancer…just saying...
For the rest, I agree with iwannacoach