Skimmed most of this. I am no expert. But, I went through the same issues early on. I believe my issue was that I thought my tank was fully cycled, but suspect it was not. I suspect mini spikes of ammonia stressing my fish out. I did add a ground to my tank. Also, was sure to blow off my live rock with a powerhead every time I did a water change to prevent any spikes. I did not blow off my rocks for the first couple months- huge amounts of junk blew off. If you said you started your tank in February with live and dry rock, I bet you aren't fully cycled yet. I would leave the damsel in on its own for a couple more months. I did this, then got the damsel out of the tank and slowly introduced two clowns. They are doing great. Added one more critter each month. I learned that even though my test all show my water to be fine, I may be having spikes in am not reading. And the tank may just not be "settled" yet.