Fortunately I only had to deal with trips or mites once but because of that unfortunately I dont wanna say its not just in case but to me it looks just like the nute burn you mentioned. The ones that can take more nutrients shouldnt get less because 2 of them cant take them, just give less to the ones that tolerate less, and after youre done fertilizing use some plain water to complement the ones you watered less with the solution. Beware of burned tips, we all get them, specially when feeding pk, but thats a sign that you reached maxium nute dose for that plant. I always have one or two that react bad to a moderate dose of nutes and I have to tune it down for those only. If you are afraid to feed them too much start by using half of what you used to, if you dont see new signs great, if some of the bottom leaves start yellowing (not only the borders but the whole leaf and without a burned tip) it needs more nutes because is starting to take them from the bottom part of the plant.