mrs weed chick,

you are 4 weeks into flowering...
your stems look great but soemthing is wrong with the upper leaves.. a little to much curling...

yellowing of lower leaves is normal : )

I would be carefull trying to change nuts at this point in the game... you don't want to fry your plants!!

your plants are "turning off", "tuning out".... you probably can't do much at this stage of their growth (that is benificial) other than .. avoid doing more damge to your ladies...

Can you see your roots? Are they soggy and dying..?

I am leaning towards some sort of over/under watering or root oxygen deprivation...