I would get to a hedgie savvy vet and get her checked out. It's possible that she's not absorbing the formula well (even though she's pooping and peeing). They should be able to examine the poo to see if she's digesting everything well.
We are as gods to the beasts of the fields. We order the time o' their birth and the time o' their death. Between times, we ha' a duty. - Terry Pratchett.
"Men have forgotten this truth", said the fox, "But you must not forget it. You become responsible, forever, for what you have tamed. - Antoine de Saint-Exupéry