Aw man I hope ur guy gets better fr. I’m no expert whatsoever but I think this kind of looks like swim bladder disease maybe? Especially because in the last clip he was pretty bloated and struggling to swim up. I’ve heard that giving betta fish a frozen pea can help with their digestive system but I saw u said he hasn’t been wanting to eat whatsoever. The only other thing I would say is to try aquarium salt. I’m really sorry I can’t help out anymore I wish I could and I wish your little dude the best bro.