The scales pine coning and lifting off his back is from an infection underneath them. The skin becomes inflamed and causes the scales to lift and if it's bad, the scales fall out.
The red patch on his back looks like a bacterial infection, but it could be a bad external protozoan infection. However, there was an infection in the dorsal fin when this first started and that might have gotten into the tissue under the skin.
The fish might have a drug resistant bacterial infection, in which case it won't respond to anything.
It is rubbing on objects and that can be from poor water quality or an external protozoan infection.
The fish actually looks quite healthy and is definitely interested in food and checking out things in the tank. The lethargic behaviour and heavy breathing is probably associated with the infection, the fish is tired and weak but it wants to live.
You could try raising the water temperature to 30C for a couple of weeks and see if that helps. Or use an external protozoan treatment that contains copper or malachite green. Use that for 2 weeks and see if it helps.
Increase aeration to make sure the surface of the water is clean and free of any films.