The pain you are feeling around your navel may or may not be related to this, but it certainly bares investigation, I would recommend you let your Doctor know about this new pain first thing in the morning.
Do you still have your appendix? The main symptom of appendicitis is pain around the belly button. It may feel like indigestion or it may feel like you have to have a bowel movement , you may also feel gassy. What to watch for with this is if it begins to move to the lower right side, if you develop nausea or a fever.
Unfortunatly, we are not always able to be certain what a particular problem is. In your case, the problem was clouded by the symptoms of your recent fall and surgery. I am sorry, but I tried to help you.
I hope you have a nice day:-)