The ram-horning of your leaves is a hint of an excess causing a lockout. Not quite pH. Flushing would be ideal, here.
your right, and thats basically what I said. Start flushing your plant early for harvest... and give some mollasses in a couple of days to help break down and use what nutes are left over until their gone or you pluck. Pull off all the dead leaves the day after you flush.
don't keep it right right next to the fan. a little bit away so that transpiration doesn't occur too rapidly causing it to suck water faster than nutrients. But not so far away that it doesn't get fresh air.
Coco coir holds nutrients really really well! I have noticed I feed 1/4 less often then I used to. I also noticed you have to be more careful with your PH in coco coir. I use coco coir too, and I make sure to mix in a decent amount of perlite, and a little crushed oyster shell. Using RO water makes a big difference with coco coir too, especially if you use it all the way through. Or at least properly treated water (there are many different methods). There isn't a whole lot of time left for that plant, so like I said it almost definitely won't make a full recovery.
But if you start flushing it now, and give a little mollasses in a couple days, it will get more dense and will allow more time for the trichomes to develop (also for the flush to get the ferts out so it has more pure taste, though taste will be affected by this trauma here).
Other than that, are you using CO2?
..... if the tops 2/3's doesn't look ok at all after a few days of mild flushes than you might think about chopping that part.... you should see some minor improvements in the upper portion though, it makes sense that it would start being more healthy from the bottom up, Cheers and 
