i wouldnt start panicking. what kind of water are you using? cal and mag might be in order...however you mentioned nothing of ph. that could be your problem and your plants are not absorbing what they need due to ph issues. you should about 5.5 in coco(from my understanding. try to find info on here for your medium. flushing may have compounded your problems as now they are not getting any nutes. go to floras website and look for a ph/nute chart, it may help out. take pics under blue spectrum as hps will hide things from us, sunlight is even better. yellowing is normal, but brown/bronze blotches and intraveinal discoloring is not. with the info you provided it could be anything. start with ph, though.