Shit that's just a strange set of symptoms all around. Running the distilled water before is what I think really shot you in the foot. The edge spotting and speckling in the center of the leaves looks like a really bad potassium deficiency or lockout. The tipburn looks like fert burn. CalMag has other trace minerals besides Ca and Mg and will at the very least help halt the spread of the problem until you can identify it.
When you did your flush, did you check the final runoff pH of the water coming OUT of the pots?