The medium you have transferred them to, it doesn't like something in there as they were flourishing in the solo cups. Best advice I have learn't from here is to alternate feeds. So Nutes with the feed one time next time with just Ph'd water no nutes. The burning on the tips of leaves looks like potassium abundance or zinc. Half your nutrients if you are putting any in. Water alternately. I had a seed 2 grows ago that nearly died from bad (new bag of) coco coir i had put it in. Something in there was killing the plant. There is a great picture on the net somewhere with pictures of leaves and their deficiencies, download that as it is a great help in working out where the plant needs help. Is it an auto or photo period?