Very dry, exfoliated scalp and hairloss.

I am suffering from the very dry and scaly scalp plus hairloss for past 2-3 years. I have seen 4 dermatologists and used products like ketoconazole, stieprox shampoo, different hair serums, some biotin and other capsules, minoxidil 5% etc. Doctors said that it is early stages of AGA. All the medications gave temporary relief and didnot work for 2nd time. My diet is on point as told by the nitritionist and all the tests recently done show normal. I also do exercise 6 days per week. In past 2-3 years i have lost considerable amount of hair, while hairs on other bodyparts are growing/coming at rapid pace. Also i have tried many shampoos (parabane free, SLS free etc) and observed that they make the scalp more dry, scaly and itchy. I also observed that itchy and scaly area lose hairs very easily and its proceeding as shown in pictures for male pattern baldness. What could be the reason and cure for this? Thanks in advance