The tank is 24" deep X 22"ht X 60" long. That's the interior dimensions of the tank. I am moving him to a 240 ( 30" X 26" X 72" ) Like I said I have tried medication without any improvement other injuries he gets (smashing the lid going for worms or misc scraps always heal asap) I do 50% water changes every 5 days.
I'm at a bit of a loss as well. Unfortunately i've never owned a tail self-biting fish that wasn't visibly sick and after searching online other people believe boredom and stress maybe the factors outside from illness. The only other potential issue outside from these 3 factors (stress, boredom, and illness) that I could find was constipation.
Since your water parameters should be good with such large WCs and the size of your tank seems adequate the only thing I can think of would be external influences. Perhaps something in it's environment is stressing it out? Or maybe it hasn't gotten use to the removal of the tiger barbs so it is still being highly territorial/aggressive especially as it turns and sees a fish's tail (fish are not self-recognizing as far as I now)?
Regardless I think a larger tank footprint and a change in environment will help significantly at diagnosing this issue. As for moving a fish this large in my experience I lower the tank's water level to 50% if multiple fish in the tank or, if it's a complete tank swap, to the tallest fish's body height/depth. Then I get in the tank with a large transparaent plastic bag (ideally one that can cover the front to back of the tank ). Pillow cases, koi socks net, or even a large tarp all work as well as the goal is to try to and scoop the fish up in one slow smooth motion with some water to prevent it from freaking out as much as possible.
Of course if that is alot of work for you I've also had success using my large rubber mesh net I use for trout fishing. Another method I've actually read about on here is using a tranquilizing fluid but it was for a large arapaima gigas and there are some risk associated with this method if you're not careful.
edit: If you use the net method you'll probably need to cover the top of the net as you raise the fish outside the water to prevent it from jumping out.
HTH