Hair Is Breaking Suddenly

by Lin
(East Providence, Rhode Island, USA)

I am 40 years old, and my hair has been thinning for the past few years. This is understandable to me considering my mother and sisters all had the same issues. My concern is not about the full pieces of hair that I have been losing due to genetics. I'm more worried about what's been happening for the past year.
My hair has been breaking around my temples and forehead. I have all one length hair (shoulder length) but now I also have "bangs" that I did not get on purpose!
My hair is not colored or permed, I only use a heat product on it once a week (I blow dry and straighten with a curling iron, not flat iron). The rest of the week I just let my hair air dry.
I don't have exceptionally DRY hair, I use a good salon hydrating shampoo and an anti-snap conditioner. I have also tried many other salon products... nothing really makes a difference.
I take a multi vitamin, I use a shower head filter, and I eat fairly well.
I have not been sick, in a stressful state, and I do not pull my hair back in a ponytail or headband, etc.
There seems to be no reason for my hair to be breaking like this. The "bangs" are baby fine. I actually have breakage all over my head (you can see the little pieces in direct lighting) but I've always had that. What's been happening for the past year is pretty severe.
I don't know what to do, what to fix. Is it my diet, my products... I'm not sure what else to try.
Any advice would be greatly appreciated!!!