What causes dry skin, hair loss, and dandruff?

Hello doctor,

I have a question about scalp issues and hair loss. I am 17 years old, pretty thin, and have celiac. I had dry skin on my face for a while but about nine months ago I immediately started to lose hair, experience uncontrollable dandruff, and my skin became dryer than ever. My individual hairs became thinner (especially towards the roots), dryer, and started to fall out consistently from everywhere on my head except for a small area above my neck.

Then came excruciating itchiness and my scalp started to produce an oil with an unpleasant musty smell. Recently, I started to lose more hair in my sideburns and temples but still experience hair loss all over my scalp (I have not had a receding hairline though). Also, in addition to dandruff, my scalp has these strange small yellow substances that are the size of dandruff but do not really resemble it. The hairs that fall out have small, yellow, oily clumps of something toward the roots and I have also gotten several polyester-like thin spirally hairs. Acne has also been bad (even when I've been off sugar, fruits, and grains) and often spreads into my scalp. There are no distinct occurrences of hair loss on my dad's side of the family. My mother's father still has a full head of hair. The only two people who have experienced hair loss in my family are my mother's two brothers. My shower water is iron-rich well water and often smells bad giving the skin on my face a burning sensation (even when we use a salt filter). I have had some thyroid issues, but I do not think they are severe enough to cause my hair loss. Does anyone know what could be causing my symptoms?