Daily luke warm baths in dilute Betadiene (add dropwise until the water takes on the colour of cold tea).
I'd do this in a tub on the kitchen or bathroom floor so any spillage can easily be wiped up without leaving a stain, and the dragon can safely crawl out.
Water about 30-33 degC.
Water no deeper than side-fringe depth.
Don't let him drink the solution. Bath for 10 - 15 mins daily to help stave off any infection, the betadiene solution will help remove the biofilm.
What I've do with my rescued injured lizards is I've torn off a shred of paper towel (like found in all kitchens) and I soak this in the solution, and gently draw it across the open injury, is OK to leave it on the injury to soak in too while in the bath.
The bathing will also help loosen up the remain shed , let the dragon get it off.
Put some raw honey on it, it's a powerful natural antimicrobial and heals everything faster than any type of ointments. I use it on my own cuts as well as any wounds on my dragons. Just be 100% sure there are no loose insects hiding in the tank.
So sorry this has happened. It is always best not to help them shed. You can get
some raw, unpasteurized honey or manuka honey to put on the affected, raw areas
as already suggested. It works great!
How is your dragon doing? Let us know how he is doing.