A large syringe from a feed store or turkey baster can work well to flush out a wound. A sink sprayer hose also works to flush out a wound, or to rinse off any Betadine or Hibiclens, etc. The Neosporin or triple antibiotic ointment is very good to apply after each cleaning.
Peroxide should not be used repeatedly for wounds, but sometimes can be helpful in one time use to soften a scab or flush inside of an abscess to get pus out.
Would it be possible to place his lower end in a bucket or dish pan of warm water, and add a bit of either Betadine, Hibiclens, or Epsom salts, and soak him for about 15 minutes to soften the scab? Then I would try to clean off the scab to see if you see solid yellow pus or just bleeding. Then...