I'm not sure what's going on, but it looks more like a nutrient problem than an insect problem. The leaves look very nice and clean.
You really shouldn't be fertilizing any plant that is under stress. I would hold off fertilizing for a few weeks, and just give them lots of water for a while. Check the micronutrient analysis on your Jack's fert, and see if it has any iron component. Dark veins and yellow in between sometimes indicates iron chlorosis. You also might check the pH of your water - if you're using well water for these, it can raise the pH in the pot too much and prevent nutrient uptake - phosphorus in our ground water actually buffers or blocks the availability of soluble nutrients from fertilizer.
What soil did you use when you re-potted? I've had some really poor quality potting soil from Miracle Gro the early months of this spring. Seemed like just sawdust and chunks of uncomposted wood with a little peat and perlite mixed in. Terrible! I recently switched to an organic brand from Ace Hardware that is SO much better. Dr. Earth Pot o'Gold - actually looks and feels and smells like soil!
Soil with a high pH or too much uncomposted organic material will actually block the plant from taking up nutrients properly. IF this is the problem (or part of it) I would try adding some organic amendments like well soaked alfalfa pellets to your pots, and watering them in. It's sold as horse food at feed stores, about $15 for a 40lb bag.
