Could My Hair Fall Be Caused By Hypothyroidism, Dandruff, Or Hair Dye, And What Steps Can I Take To Prevent It?

Question: I have dry hair & light dandruff, I have the habit of doing a head bath daily, if I don t do it for a day, my scalp becomes very irritating and itchy. Recently I am suffering from a hair fall, I am losing 40 to 50 hairs per day, I don t know whether it will be replaced by the new ones. Recently I am affected with hypothyroidism (well in control). I don t understand whether the hair fall is happening because of dye that I am using to color my hair or because of thyroid or maybe due to dandruff. If I use a dandruff shampoo, God knows about dandruff but I am losing excess hair than normal. Please suggest to me a proper solution or any initial advice take, for preventing hair fall.