Yeah its mainly on the new growth. This is one of the toughest strains ive grown.
Yeah it's nuts how some strains can be so fussy and others would thrive even if you pissed on them!
I stopped growing Barneys Pineapple Chunk because it required an entirely different feeding regiment from all my other strains.
You will figure it out and get it sorted, and it could go on to be a winner.
Are you soil or hydro? I'm in soil and if I were in your shoes I would give a heavy watering of simple ph'd water and when the pot drys in 6 or 7 days give it a simple light feeding of fishmix and alg-a-mic, this is a sure fire way to get things back on track.