I recently have a similiar situation!! After falling, the best thing you can do (if you have not been hurt) is to get back on the ride. You should pass time with him for he gain your trust but it will take some time and patience. Good luck
I actually had the same experience so I feel you!! That happened a year ago and what I did was I just kept riding. Maybe not ride the same pony but I kept just riding and after a bit I started to ride that horse again. Also lunge him, and do groundwork. Spend time around the pony and slowly you will build trust and gain back confidence.