dolomite lime will stabilize your soils ph at 7,and a stabile ph makes for more efficent uptake of nutes.adding it will make your grows go much smoother.you can find it at home depot or lowes it is sometimes called garden lime,and it is normally added at 2 tablespoons per gallon of soil.you can still add it just sprinkle on top of your soil and work it in a bit and water it in.also i beleive the dying leaves are not from n def i beleive you are overferting your plant in the pics i see alot of burning tips and dying leaves.on next feeding water only with water.you may need to flush if it keeps getting worse.