Did it every self correct? Were you able to keep healthy montis and birds again?This is actually very similar to what happened to me - after the lemon-peel
I tried so hard not to overreact and dump chemicals in the tank. I tried thwt with an algae problem in an old tank with fluconazole, vibrant, hydrogen peroxide, etc and it was a never ending battle. The more I did the worse it got and it became a lost battle where coral just couldn't survive no matter what I did.
When I noticed issues I chalked it up to the pesky lemonpeel. Since before her introduction things were great i didn't make changes or do anything different. My numbers were all stable and where they had always been. I tried to just maintain stability and let things work itself out, nothing great comes fast. After 5 months though and no improvement I had enough and started trace elements. Also picked up my waterchanges from 5 gallons a week to 15 to try and flush whatever in out quicker. Finally I looked at my log and noticed before the decline I ramped up my kessils in my t5/led hybrid. I turned them back down to lower levels. I also had a lot of sponge growth in my sump and have heard of issues with sponges and toxins, cleaned and scrubbed the sump and refilled.
After starting all that a few months ago things did improve and as mentioned my stylophora regrew its skin, green slimer starting growing again, lps looked puffier. I've continued on this path for months now and although a lot better things still don't seem to be quite right. Just trying to figure out this last peg and not overdo anything.