Most of my balls defacate the most (or only) when they shed. If you saw signs of an impedding shed then more then likely that is when they will poo/pee. Balls have excellent digestive system and they can extract every ounce of usable material from their food....so it can take several feedings to get enough that they need to get rid of the waste. I have a large 5' ball that has eaten 10-12 times and still hasn't poo'd but lord help me when he does go. :eek:
As for shedding usually they turn "blue" or hazy then a few days later clear up like nothing happened and then a few days more they shed (most of mine take 7 days from start to finish to shed)
As for the belly a pic would help.