Why does my hair break at the nape?

My hair is waist length and is naturally poker straight, i dont heat style it, use chemical products or anyything, i use a natural shampoo and conditioner, i have a satin pillowcase to stop hair breaking, i dont wash my hair everyday, but every other day, i dont comb it when its wet, etc basically i prettty much take care of my hair, i even take vitamins for it!! The only thing is i dyed it about a year and a half ago , so the bottom 3-4 cm are dyed, but even the undyed hair has breakage, its only like the very back layer, the rest of my hair does not break or even have split ends, the back of my hair like a very small portion is frizzy dry and has breakage, i hate it feels ugly and like straw. Is it always gonna be like this or is there something i can do?... oh yeah when i was younger it was never like that? Oh yeah i really dont want to cut my hair, as im trying to grow it and the rest is healthy.