yeah could be but i hope he recovers
I'm sure he'll be okay! Betta fish are incredibly hearty, and I've heard they're mindful of their owners. I'm sure your betta appreciates you.
I had a betta fish that I rescued from the LFS and kept for a few months until he began getting strangely sick. I never was able to pin-point why, but he was definitely aging. He lost a lot of body mass, and his fins began getting thin/skinny (he's a veil tail). It came to a point where he was just hanging out at the top of the tank, barely moving, but he would still eat and try to respond whenever I was nearby. I also thought he had swim bladder disease because he started sleeping on his side a lot.
I could've sworn he was going to die of illness or old age since he hardly moved. I ended up putting him into a separate fish bowl that I could keep dark (kind of like a hospice) since he seemed most comfortable hiding/in dark spaces.
For some reason he's doing better now, and he even has that notorious 'white pimple' on his head that supposedly reflects that they are aging. He sleeps at the bottom of the bowl under a rock and comes out in the morning when I feed him. After he eats, he goes right back underneath the rock. Pretty cute, and I'm super happy that he hasn't passed yet.
Sorry for the long story - I think I'm just trying to say that it's trial & error, but don't give up hope! As you keep monitoring your betta, you might find out more of what he needs, and be able to help him in that way.
Hopefully what I wrote makes sense, lol. Good luck!!!