I've been having the same problem. My hair is very dry and very thin. I use a super wide tooth comb and only use the low-cool setting on my hair dryer.
Also when washing my hair, I wash very gently as not to loose hair in the shower.
A few pointers, don't use hot or warm water to wash your hair, only cool to luke warm. Also don't use shampoos that contain sulfates. I've done ok on Biotin Shampoo, has all natural ingrediants.
I also apply two beaten egg yolks to my scalp and hair and massage in, leaving in for 10 minutes, than rinse only with cool water.
I'm taking Kelp regardless, as it has iron and natural Iodine
in it essential for hair. Biotin taken orally also helps. But, basically, it's all part of the severe stage of AF, which I'm in too and it's effected my thyroid big time and this effects hair and skin.
I really freaked out in the beginning, but am dedicated to my AF protocal and also using any hair measures too to prevent loss and encourage growth.
Look on internet for sulfate free all natural shampoos that are fortifiled with vitamins.