I've been unable to battle since yesterday, my pet is full, happy, and has all her hit points. Am I missing something?

Check here to see if your pet is already in a battle. :U If they're not then you should file a ticket.

Double-check that your pet isn't already in a battle.

To do so, go here.

That was it, thank you! Site went down last time I battled and I forgot about it.

Glad to hear! Locking this as resolved. :)