TBH your ph in soil is out of wack due to feeding,, and soil building up with salts. burns start at the tips and work there way in looking at your leafs this is not the case
pending on how far you are away from harvest ??? what i would do is flush plants with medium nutrient solution 600- 700 ppm ph's 6.5 - 6.8 3 times the volume of soil ,, catch your runoff in different stages and test ph you might be surprised how out to lunch it is ,,,, causing lock out cause right now your plants are not making buds but transfering what energy it has into survival mode and repairing it self or least trying to
FLUSH FLUSH FLUSH