looks like a lock out for sure. You are better off doing a weekly or at least every other week flush with plain water, water with carbs, teas, or expensive PK boosters. When you feed high PK on top of the rest of the feed regimen, it is easy for the ppm/EC to be too much for the plants to utilize, so this is when you burn. If this continues without a flush out, or at least a light feed to rinse out the salts, you will get lockout. Always pH your water so that the food you feed is available.
Also, looks like you have some mites, or at least mite damage. Maintenance sprays are your friend. -Cheif