I used to be able to go at least a week before I needed to wash my hair
Tbh, I could have got away with longer, but that would have been icky. Unfortunately, it's definitely true that the more you wash your hair, the more you need to wash it. The thing is, nobody wants to walk around with greasy hair, so it's a tricky cycle to get out of.
Anyway, now I wash my hair 2 -3 times a week, but I would need to probably wash it every day- every other day. I've tried silicone free shampoos, shampoos for oily hair etc, but they don't really make much difference.
I think OP's dd's situation is different though, as it definitely does sound hormonal. Is she having any other hormonal symptoms, such as mood swings, acne etc? I would have thought that if it is some kind of hormonal imbalance, then this could be helped if you go to your gp, possibly with medication, but I'm not an expert. For now though, I would suggest that your dd washes her hair in the morning and not the night before. Make sure the water isn't really hot, don't use too much conditioner (maybe she doesn't need any) DON'T massage your roots too vigorously, gently massage, but not for long and don't use conditioning shampoos. Also, suggest that she doesn't touch her hair much.
Really hope this gets sorted for your dd. We all know how tough those years are and a problem like this is going to feel huge to her. Has she been to her gp?