Good to hear Sunny is better before I even noticed he was under the weather. I hope Starr doesn't keep him from eating. Poor boy.
Regarding Pearl - Tigris has diarrhea once in a while. Last time it was really 3 or 4 days in a row. Our vet say that this can really mix up a cat so it should be treated- and what she recommends in an otherwise healthy cat is just having it fast for some hours or even a day. With Tigris last time it certainly did the trick. He was of course a VERY hungry boy after 12 hrs fasting but next day it was back to shaped tootsie rolls and has been like that for two months now.
Good luck with your kitty family.