squabeggs, I can't for the life of me think what this could be. Nothing comes to mind that would 1)cause that kind of spinning and 2) improve with antibacterials. The only thing that MIGHT be possible is an infection in the gut, some kind of bacteria that's releasing air into his bowels and causing him to uncontrollably roll onto his back, where he struggles back upright, then rolls over, then back upright, etc. I'm glad to hear he's on the mend though. Keep up with the treatment and be sure to hold those nitrates down. Best of luck to you and him.