Wow... Dont look good at all buddy.
For starters that 2nd pic. Go to thatb nug and inspect the top half of it for bud rot. Like grab the nug and open it and look for white fuzz or webs.
2nd I would suspect root issues from the pic so take a look at tjhe color of your roots if you can.
It's not rot, got burn the first week to close to light when it shot up very quickly..... just where I cut the burnt bit.
It's just weird the one plant is doing this when the other plant beside it was fed the same amount and shows no signs. Knew I shouldn't have done one last feeding....