Answer:
It's hard to judge why your dog is confused. He may have eaten something weird, but you wouldn't know from that one symptom. If he has diarrhea (if his poop isn't solid), then it might mean he's eaten something bad but it usually doesn't result in confusion, so I doubt he ate a frog. If his sleeping, eating, and living habits change, then you should seriously consider the problem...
Your dog may be confused from a fear of something, which I think is most likely. I suggest you take a few hours to spend some time quietly with your dog in the backyard, with little interaction. Soon your dog will wander off on his own, and then you might find out the problem! :)
Another possibility is that your dog might be sick. If you have evidence leading to your dog eating a frog or something else, then maybe he caught a virus from that.
I'm pretty sure that your dog isn't seriously in danger, but remember that you should always have your vet's phone number on hand!