Well for a "novice", you seem to be pretty on top of your game. Ph is good and everything, IMHO.

Except the amount of ferts/food u r giving it. seems to be a tad higher than what i would recommend. Try doing it less. thats sadly all the advie i can give you

-G

p.s: i have the same problem with my plant. It was turning yellowish green at the tips, then it turned brown and died at the tips. And only on a couple leaves at the bottom. The problem was not overfeeding, persay, more that i mixed two kinds of miracle grow soil. not the smartest move at all. =) nevertheless, it WAS a fert/food problem. I resolved it with a soil change. expensive, but effective