Poor Posiden! I think he has body rot!

He has a pach of scales missing and it looks like hes suffering. When ever he toches any thing he always flinches away like it hurts.

Hes sleeping alot more than usual too. (always behind the heater or filter) Im starting him on some betta revive in a small holding tank. Im going to start changing the watter 100% 3 times a week. (It did not start out as fin rot)
If you have any tips on how to help my poor babby pleas dont hesatate to inform me.
Pleas no rude coments. Thank you.