Soft water here, and no problems like that! So it might be related to hard water.
But the longer you go without washing, the more hair you're going to dump when you finally do wash it. Your head normally loses several dozen hairs a day, and that adds up really fast if you're talking about a week or more.
Steak, eggs, potatoes - fruits, nuts, berries and forage. Coconut milk and potent herbs and spices. Tea instead of coffee now and teeny amounts of kelp daily. Let's see how this does! Not really had dairy much, and gut seems better for it.