Severe hairfall and loss, no growth.

Having a lot of hairfall since 3 years. Shifted to Bangalore in 2019 June. Due to weather change and humidity started having a lot of hairfall while hair wash. Till feb 2020 it became extreme. Tried onion juice, different shampoos but nothing worked. After coming back to my hometown in covid, I thought situations will improve since I've been living here and never had any such hairfall problem. But it still didn't improve, tried aloe vera and other oils and different shampoos. I have oily hairs, and if i put anything in my hair it'll result in a lot more hairfall while hair wash. So i even stopped putting oil in my hair and just washed normally with shampoo. If i use conditioner then also I'll have more hairfall than usual I consulted a dermatologist for 2-3 months but still not much improvement. Had blood tests for b12, thyroid, vitamin D, hb. Everything was normal except vitamin d which was low than usual. Now my hairs have even stopped growing. Tried taking biotin but not working.