Re: car seats and kids
All car seats are not equal. Perhaps a different brand/model car seat would be moe comfortable for her.
Is she is the little kid type car seat or she sitting in the older child type seat?
Like adults, children need to sit in a comfortable well fitting car seat.
Does your daughter complain about the seat only after she has been to dance/gymnastics? If so, the activity may be aggrevating a problem she has.