Science Fiction. Killer nanobots, had several MC’s that eventually met up over the course of the novels, each chapter started with characters name and the date, I think the time was included too

[Ray]

I read this book a long time ago through Amazon prime, before Kindle unlimited was introduced.
The author is smaller, or was when this was written, as he had left his email at the end of the book. I emailed him to say how much I loved the book, and he sent me a copy of his next book that was a mystery, unfortunately, I cannot find this email anywhere.
The nanobots in the books are just out to kill, they do not grant people special powers or anything like that.
Please help me find this book, thank you for all the help!
Let me know if I’ve forgotten to add anything, as this is my first post on this group forum!