I went into battle quests today and it says none of my pets are able to fight. My main pet I use for battle is checked into the resort as of about a week ago for the full 21 days (I also checked to make certain that something hadn't happened and he had been checked out for some reason). I also attempted to play with him and feed him and it gave me the messages about him being too happy and too full. I was able to do battle quests yesterday without a problem.

That was it. I swear I had gotten him healed after trying to take on an event challenger, but apparently I had forgotten