I think that is Potassium toxicity. The plant is no longer feeding. All systems have been shut off. You can put it on a diet of calmag at 400 ppm 6.2 for a while to help it finish. It will no longer process any notes you give it and they will just build up in the medium. You use the calmag as sort of a flush and to at least restore ph levels. You'll still get stoned on the weed.
it may be over fed or watering ,but as @Talkative has said it could be Potassium doing what he has said wont hurt the plant or the weed to smoke ,,,,,,mac,