Deficiency or nutrient burn?

I think that it is nutrients lockout in your soil, do you control your PH? You can try flush with 6.5PH pure water and then you can add nutrients.

Did you let the soil dry up once too often? If so, this look typically is from drought in the soil. Just keep up with keeping the soil moist when she's in this stage. As any dry spells the plant eats itself. Typically though id look to see it much lower. So, I gather it started from the bottom? If so its drought and roots were sucking dirt for too long and the plant has eaten itself