Hi KellysMommie and welcome
That is so sad, I have no idea what could've happened either. This is the first time I've ever heard of a Beta sharing its home with another living creature... and they lived. Hmmm.. guess anythings possible. My step daughter has a Beta and decided to get a goldfish(in its own bowl) and set them side by side. Its so cute, they hang in their bowls next to each other... I'm sure the Beta is probably saying "let me at him!" LOL. But they seem to be keeping each other company

. Good luck with your guy.