agree-back the light way off. Flush until the runoff is under 200ppm and the top it off with 400ppm.All the old damage will get worse and die that's normal. You flushed and the go back to feeding 1000ppm? The flush was to fix the overfeeding to begin with. Light is still to close imo because of the plant health.
Have you looked for mites?
Back that light off... not 3" but back it off to like 30" and let then recover... when plants aren't healthy and you keep pounding em with light the only thing you gonna do is make it worse.