Brain injuries bleed internally and it's a closed cavity so no real space for expansion to accommodate a leaking blood vessel.
Causes intense pain and rushes of heat to head.
I know because I had one (and it's the cause of my spelling words backwards here sometimes)
It is speculation in Jason's case but it fits the picture too well... for dismissal as a theory.
I'm still not sure of location of pond in relation to where he dropped his clothes? Left or right?
He might well have been going to get water for his fish.. but the fish was probably dead at that stage, his container was with the toiletries.
https://www.facebook.com/Caldwell-C...16/photos/pcb.749910755634048/749900552301735