You may check the original image after editing by pressing the "\" key on your keyboard in the develop module.
Please let us know if it helps.
This only works if you haven't used the command "Copy After Settings to Before" and a few other things that replaces the "Original" settings. There are a couple of ways to reset the original settings to BEFORE but you have to be careful you do not lose your after settings.
Thank you, Mrinmay! Your solution is very helpful!