I do appreciate that multi-cat households can make monitoring urine/feces difficult. Still, if you are feeling a ball like mass in the back portion of the abdomen, he is crying/uncomfortable when it is palpated, and we have not seen urine from him; then I'd be very concerned that Prince may actually have a blocked bladder. And this is an emergency situation.
When we have male cats who cannot urinate it is often because of a urinary blockage (crystals, inflammation, spasm, etc). These cats will often seem fine initially but perhaps show hiding, increased trips to the litter box or straining to urinate (in the box or at odd sites), and licking of the irritated privates. But as the bladder fills, they can become painful, vocalize, be lethargic, and even depressed/collapsed. And as time goes on with the bladder blocked, we see urinary toxins leak back into the blood. This can make them feel worse, vomit, refuse to eat/drink due to nausea and discomfort, and it can even slow and stop their heart (and be fatal) if not unblocked and emptied immediately.
Therefore, if he has what feels like a firm filled bladder at that point in his abdomen (you can compare this feeling to other cats in the house...all can have a degree of filling but likely won't be as obvious as his) and he hasn't been seen to urinate recently, then I would strongly advise getting him seen right now (by the ER vet if your vet isn't open).
In this situation, it would be prudent to get your wee one to the emergency vet. To find one local to you, you can check
http://www.veccs.org/index.php?option=com_hospitals&nationid=1&Itemid=193 and @ http://www.vetlocator.com/.
Please take care,