Do you still have planaria? I had a massive slaughter of snails when I was recovering from surgery when the snail tank developed planaria. I will have to look for the article, but I once read that planaria can sting. Its possible if they are still there they are part of the problem. The little darting things are probably copepods. I am relieved to hear they were fine in your community tank. How long is left to your ich treatment? Since those are baby snails, I am very concerned that they are not eating. they cannot go as long as adults under stressful conditions.