I never used nutes with a pot that size. My lower leaves started dying. I transplanted and all my problems went away. 3 weeks later and I am getting deficiencies, time to start feeding.
I found that a rootbound plant gives strange symptoms. Move to a bigger pot after flushing, transplanting alone will only move the problem to a new pot. If you are using chemical fert in an organic soil, the organic part of the soil is now moot. If you have too many salts, pH your water and flush until your run off is a decent pH and you have low ppm. You need to get rid of the salt build up. Then add proper nutes.
Organic works differently. Chem fert = a couple flushes during the growing process.