They look possibly overwatered. Also they might be experiencing transplant shock- I have rarely seen it in cannabis but it is possible.
I'm wondering about your fertilizer too. 20-20-20 is not a good mix for cannabis in any stage of life. You need a lot lower P and K atm, but you still need the micronutrients, so a cannabis-specific fert is the absolute simplest option.
The last thing I would double check is that the ventilation is adequate. Adding another fan might not be a bad idea.

Wait- looking at the pictures again, when you transplanted, did you bury the stem deeper than the node where the cotyledons originally had been? That's good for tomatoes... but weed does not like it!