It looks like a feeding issue… Are your other plants having the same problems, or even showing some of the signs as this one did before it got to this point. It may be over feeding. Good luck none the less dude, it sucks when you get set back like this. Give them pure Ph adjusted water for a couple of feedings, thin switch them back to the food. Make sure your ppm’s are low, but not to low then work them back up and that should fix it.