Drastic Hair Loss, Photos - Now & Then.

After shifting to kota, I suddenly changed my hair washing cycle from everyday to once or twice a week. A white greasy itchy thick layer formed around the scalp. Hair started falling in bulk quantity (300-400) strands while washing, even while running fingers through hair, it just comes out like if it's not attached to the scalp. The blunder was that I did not take action for 5-6 months. I had extremely dense rough hair. After this happening I had only 30% hair volume as compared to earlier. I visited dermatologist and used ketoconazole shampoo and topical salicylic lotion. It's been 3 years now, I am in mumbai from last 2 years, kept scalp clean by washing hair everyday with mild shampoo or with prescribed shampoo (if itching occurs). I'm not just satisfied that how can a person loose 70% hair in just 5 months? If hair follicles remain constant, then why 70% of my follicles are not producing hair? Is there any little hope of getting that volume back? I think this is not hereditary.