looks much better now, this does however keep me thinking he found a spot to rub onto !!
try looking for a sharp edge, sometimes the screen top has steel mesh that stick beyond the rubber gasket they use to keep in place !! run your fingers all along them.
or if the top isn't locked properly, the snake can push enough to lif it and get his nose/head stuck, then the only way back is to pull and then injure themselves..
it could be something else too.. but from what i see , it looks to be something in that order..
look for
-screen top edges
-loose top (sometimes they don't clip perfectly) push from the inside out to see
-the exo terra vines if used, they have a metal wire inside and it can protrude when bent
-something you're using to hold perches,vines
-a piece of wood with a jaged edge
-damaged water bowl
the list can go on
and you may never find it !! plus as i said , might be something else..
you can help him with that triple antibiotic polysporin to prevent infections.. just use a little and apply it with a Q-tip
after a few more sheds, the scales should grow back and he will look pefect again.
what you see is the skin and i think the black spot was dried blood..
other possible thing i just taught of !!! did you leave a live rat or mice in there that could have defended itself ?? either scratching it or biting it ??
nice GTP by the way :-D looks like a Wamena local with the blue triangles along the body..