i believe there are many things going on here. 1rst -your soil mix is to high in nutes, then you add more nute to it when you feed. I would bet that if you got a ppm meter and tested your run off its up in the numbers, witch you get the burn, and then you get nute lock out, 2nd- then theres a your pot size, root bound, when you pull these plants i bet the roots have taken all the room up in soil, this is not the first time its happen to you so , its your mix no dout. 3rd- in flushing use 3 times the amount of water that your pot can handle. 1gal pot use 3 galons of water. this is were you can check your run off, to see how high your ppm is. i would start there. the more you flush them the lower the ppm will get. but let them dry up a bit before you flush again. my addvice would be go with a soil you dont half to mix, like fox farm ocean forest.