I had a similar problem with crusting flaking scalp when I was seventeen. Like yourself, it caused me to lose a lot of hair.
T-gel and head and shoulders didn't work for me either. What did work however, was Nizoral shampoo . The skin condition cleared up within a few weeks and eventually all the lost hair grew back.
You should at least give it a try, and perhaps taking a multivitamin supplement might be an idea too.
Of course.... several years later I developed male pattern hair loss.... but then that's another story!
Hope this helps.