Hm, it might be the soil, then.

Some of the first pictures you posted with the plant's fan leaves curling inward and down told me it could be over watering, maybe even improper soil aeration. The soil has to be nearly bone dry before watering again -- Mojave desert, cremated man's ashes dry.

The plant has to be just on the verge of getting to wilting, but not so much that the turgor pressure is causing the plant to noticeably go limp.

What kind of mix do you have? You said something about having a clone in Fox Farms soil. Are you using that, and if you are did it include perlite, or did you add any?

Another likely possibility is the soil has got too much food in it. Do you have a TDS meter, maybe something that measures the water hardness?