He's probably just scared from the experience! I'm sure once the "shock" wears off he'll be ok. Take a breathe and try to relax (I know that's hard) because he can pick up on your emotions. The best thing to do IMO. Is to slowly start to re-introduce the outside area to him, once he's had time to relax and calm down himself. Maybe take him for potty breaks in front for now and slowly walk him around back? Hope this helps.
Good luck!