Thank you pheonix for your help!
And to juice, I've read a lot that bettas rest lying down. Is it normal for them to spend 90% of their time resting? Additionally, when he does swim sometimes it looks like it's really exhausting for him. I had hoped some food in his belly would help
I will alternate with the filter and, until he gets better, only have it on when I can monitor him and make sure he doesn't get stuck. I read that bettas can go 14 days without food, but it's making me anxious how quickly he has declined over the course of two or three days. Are there any food alternatives I may be able to find in my house that he can try?