if it were just the spine I would be inclined to agree with your hsuband, but if you can see lesions as well then I'd worry about fish TB. It could be mouth-rot due to stress from a spinal injury - dojos are prone to mouth- and fin-rot - but if it's not responding to antibiotics and you've tried more than one kind then fish TB is a possibility.
google has a lot of fairly reliable info on it, but be aware that if this is your culprit then the prognosis is poor

. It's also likely the other fish are carrying it, so don't add anything new tp the tank for a while - and be aawre that it can cause a very nasty condition in people, too.
hoping I'm wrong,