at first sight the curled leaves makes you think ph and nut burn but after reading you flushed heavy with light feeding im scratching my head. When i have issues like this i like to use a casting tea or compost tea. they love it and it's hard to over do it. go back to basic and good luck.
I had the same problem with about 2 babies in my garden. At the time it happened I had just repotted, with no nuts just miracle, worm casting and perlite. I think it's overwatering and possibly not draining fast enough. If you have problems and it drains quickly enough you can clear most...
man thas gonna be some raggedy bud. Its hard to get the density that you need to really turn it up. You'd be better off getting a 250, like 10 inches and going from there. Good luck