S-Shaped Spine on Betta

Can someone help me figure this out? I bought a Male Platinum Dragon from Petco 2-3 days ago. When I got him home I noticed he only stayed at the bottom and he swam up to the top decently, but it looks like his back is just dead weight and he had to move his fins extra hard to stay up. Whenever he goes to take a breath of air he starts to float vertically, and he'll just boot scoot across the bottom. I gave him a break from food for a few days to see if that'd help and nothing changed. I understand that all of this points to sbd but I've never dealt with anything other than it being constipation. His spine is curved in a s shape and that's a first for me. He'll also just lay at the bottom and stay hidden or stay near the top but no matter what he always sinks and can’t stay up for very long. I’ve also caught him bumping into the thermometer and one of the decorations when I first put him in the tank.
His name is Zuko and all his perimeters are excellent, and I've had the tank up and going for a while before he came along. I have a moss ball and an amazon sword in the tank and previously I had different betta in the tank. the temp is at 78 and he's the only fish in the 5 gallons but I drained it to half, so he didn’t have to struggle getting up. I haven't used any medicine but I use prime as my dechlorinator.If you could provide any useful information no matter what it'll be very much appreciated! Thank You!! ^-^ PS he had a s-shaped spine and looked a little off in the store.

 

Might be TB. No cure for it that I know of. Make sure you wash your hands after water changes, it can cause rashes in humans.

 

Might be TB. No cure for it that I know of. Make sure you wash your hands after water changes, it can cause rashes in humans.

Ok will do! Thanks!

 

It could also be a deformity. Most breeders cull any fish they notice with major deformities like this but the petsmart/petco breeders are breeding for quantity so honestly I don't think it would surprise me if they missed one there is just a LOT of fish going through.

 

It could also be a deformity. Most breeders cull any fish they notice with major deformities like this but the petsmart/petco breeders are breeding for quantity so honestly I don't think it would surprise me if they missed one there is just a LOT of fish going through.

I was thinking that could be the case or maybe he was bumped around during transit. Although he doesn't seem to be in pain but then again I can't read his mind. Thank you for the feedback!