What size pots are you using? Looks like maybe root lock, I would lay off nutrients for a week and flush them with a few gallons of water test the soil ph and fix it if need be , need to and just let it try and shake back.
Did you ever have a over watering problem ? I had that same issue and I had to take plant out of pot, cut away some of the dead roots and transplant in bigger pot and let it bounce back. Hit it with some recharge and she was great.
Good luck