Like I said it looks like boron deficiency but could just be your pH is too high. I would knock the pH of your next watering down to 5 to help balance the pH in the root zone. Just water tho. No more nutes until this gets figured out.
What are you using for water and what is it's pH and PPM before you do anything to it?
And what are you using for light? I'd almost say light burn bit it's not in the right spot for that. Very top leaves will start fading at the highest points first not at the droopy ends of the leaves. Not nute burn yet or you'd see burnt tips and margins all over the plant on the bigger leaves.
It's most likely micro deficiencies caused by high pH if anything. You don't spray your plants do you? Water on the ends of the leaves under bright lights could be causing what we see if you do.
I'm off to bed and will be back in 6 or 7 hours. Don't panic.
Go read my journal while you're waiting.