Chemotherapy Hair Loss

My hair is falling out and I’m very sure it’s due to poor diet because I’m only 16 and it started when I became vegetarian, will the hair grow back if I resume a healthy diet or will this just reduce the hair loss?

I’m young only 29. I take thyroid meds and have a vitamin d deficiency. My hair is getting very thin What should I do to help it!!! Im a female.

My doctors have run labs and everything looks alright, but my hair is falling out. It comes and goes so its not like permanent hair loss. I have been taking a daily vitamin with no relief. Any advice or suggestions are appreciated. Thanks.