Eumelanin Increase??

Hi 👋🏼, sorry if I’m posting in the wrong group or not mentioning stuff the right way...this is my first ever post. 😱 I’ll try to give a bit of a background before my question, if you want to skip background info, I’ll start the question in a new paragraph.

Umm me and my SO have been trying to get pregnant for 4yrs now almost going onto a fifth year. I have yet to find an OB that’ll work with me and my SO and so I’ve been mostly on my own. My mom has Endometriosis and needed an RH shot at 6months pregnant, and took 5yrs to conceive with the help of supplements. I have no supplements and have irregular, painful periods. I have not been able to figure out if my SO or I are sterile. So I don’t even know if we can even have kids in the first place 🤷🏽‍♀️ But since I’ve been having such trouble finding a helpful OB, that’s been a moot point. When I was younger, my hair color was a dirty blonde/brown and when I hit adolescence, it darkened to an almond, almost reddish/brown color. I’m almost at the end of my 26th year and my brown suddenly changed to a very dark black color in a matter of days. I’ve looked up that an increase in Eumelanin can cause this change but everything I’ve tried researching only mentions how to increase it or what happens when it decreases.

My question is: what other causes can increase Eumelanin so suddenly in hair besides a potential pregnancy?

AND PLEASE NO FIGHTING IN THE COMMENTS OR TROLLING MY POST, YOU NEVER KNOW WHEN SOMEONE WITH A MENTAL DISORDER WILL READ SOMETHING AND BE TRIGGERED. THANK YOU. 🙏🏼☺️