I have gone through major (traumatic) hair loss in the last 3 years, and I noticed it not long after my diabetes DX. However, I have had a lot of stress during that time also, am 63 (menopause), and who knows what it's from.
I spoke with 3 GPs, an endocrinologist, 3 hairdressers, a dermatologist, and any random people in the street who would listen to me. There was no consensus, and what I learned is that hair loss is tricky business.
Most thought my hair would come back and had fallen out due to stress my body was under (it didn't), many recommended Rogaine for Women (that lasted about a month until I got sick of it and thought I'd rather hold my head up high and be a bald woman than apply that frantically 2x/day), and some suggested biotin but I learned few are deficient in it and only in those cases does it work.
The body can go under great stress with an illness, and when our bodies need resources for repair, hair can be the first thing the body lets go of while it attends to more critical things. i'm being treated for hypothyroidism now, so my hair could come back in time, or some of it - but don't know.
Is there balding in your family? I'd look to your dad first for hints, and then get testing for testosterone levels, thyroid, and maybe see a dermatologist? But, expect you might not get consensus or clear answers on this.
It bites. I know.