OMG stop everything your doing and listen, i had the same problem, same soil, ak48's which i have going now!, your problem is Mag/sul, Go quickly to a store and get some epsom salt, and use a half a teaspoon per gal, QUICK!!!!!!!! Same problem happened to my babies, they were just stunted and all leaves set has a problem, and i read all about it and gave em some epsom salt and BAM there back to getting good in a week, our problem is the miracle grow, they dont have any mag/cal, so quick, go to the storre, it cnt hurt your plant, it can only help, but it is the cure my man