Solutions for Hair Fall

I’m looking for solutions for hair fall. I lost a substantial amount of weight in the last few months and noticed that with that loss my hair started falling out at a higher rate than it’s ever fallen out before. I just got the VT Cosmetics PDRN Reedle Shot Brush Hair Serum to try, but it’s too early to see results. It’s nice and cooling, and smells great, so that’s a bonus. I also take vitamins to make sure it’s not a dietary deficiency causing the issue. What sort of shampoos should I use, or other products? My hair used to be so thick and now it’s just…not. I miss my volume.