multiple things could be the problem
do you keep a fan blowing directly on your canopy? if so dont cannabis does not enjoy that.
you most likely have some problems with the rootzone. first off your tops look like they’re nitrogen toxic and overwatered but its most likely lockout and overfeeding happening in the soil. you dont need to blindly add calmag and you’re using too much to start with. too rich soil is not something plants like and mostly autos are even more sensitive in most cases so too much salinity can burn their roots and rot them
i dont want to turn this into a long winded unreadable academic paper or something so i’ll just share my 2 cents.
-drop the cal-mag
-remove any fans directly blowing on the plants
-cut your feeding in half
-saturate the soil everytime you water and only water when they get significantly lighter
-dont let them sit in runoff if you’re
-dont take any advice of growingladyfromeastmidlands seriously
these measures should improve their health and help them bounce back in the coming weeks and hopefully bulk up nicely