I have attached a clone off a Bubble Gum strain. The clone has been topped and is in a 12 litter fogponic unit, PH 5.8, using GH nuts. This clone is growing single leaves and has what looks like a rash on some of the leaves. none of the other plants in the unit have these symptoms.
Plant looks like its stretching for light.. What is your ppm? I had the same problem. Going through my check list.. My water temp was too low @ 61 and ph was on the low side. I fixed my water temp and all was well. I'm not saying that's what your problem is.. Would need more details