I have the same problem, almost bald on the crown, not sure why this has happened suddenly, but i wondered if it was down to heated rollers,i have used whioch did get very hot indeed,or velcro rollers, which do seem to pull abit of hair out with them, but i have never seen lots of hair in a comb or in the plughole after washing it,or in the shower
I bought some Roots shampoo and conditioner with special spray to encourage growth, but the spray bottle collapsed and stopped spraying, so just using a dropper for now,
Also just sent for some Minoxidil, [Regain for women] trial size from Amazon,will try that when it arrives,its about the only thing i believe works, but you have to keep using it,and expensive ,but hoping my hair will grow back, also could be stress,had a very stressful 2 years
I realise this is an old thread, but might help someone