I'm with Rachy on this.
Elpgal, I apologize, I forget your age. I had massive hair loss back around age 40 when I abruptly had to go off the pill. We're talking large clumps coming out in fist fulls, clogging the shower drain, empty patches, etc. Oddly enough the gray/silver hairs didn't fall out so I looked like I was quickly graying. They were unruly and coarse and curly.
For about a year I stopped brushing my hair entirely. I would just use my fingers. I also stopped blow drying and just let it dry naturally, which meant it would curl. Curling made it look thicker. I did get frequent cuts (this was the first time I went to chin length), and learned to part my hair in a zig zag part.
The hormonal freakout passed and my hair grew back in again-- thicker than before.
In my case it wasn't any sort of vitamin deficiency, it was straight up a sudden hormonal change going off the Pill abruptly.
I did try Rogaine during that time but it was gross and I just couldn't deal with that.