Plant starting to claw 16 days flower HELP

My one plant, island sweet skunk, is starting to show signs of clawing. The looks very healthy overall. I'm using ocean forest soil in 5 gal pots, transplanted about 30 days ago. They've been in flower for 16 days. Haven't used any nutes yet, just phd water. I'm thinking its too much N. I'm thinking g about flushing but I don't want to release any more N from the soil. Anyone have any ideas? I was also reading it might be rootbound but its only 2 ft tall so I don't think that's the problem.
 
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