K.I.
My son had the same problem
Flat head in the back and too wide in the front...
We had a CT scan done, that showed their was nothing wrong inside his head, just cosmetic shape.
We had him fitted for a helmet...he sweats a lot and it was very uncomfortable for him (got too hot.)
He wore it on and off for about a month, maybe six weeks
we stopped after that, it was supposed to be 6 months but it was not easy for him..
Did it help, I have to say yes...his head is a little flat
in the back, but looks normal with hair and you wouldn't know....I think it did help even for the short time..
Good luck
K.