Gum color should be pale pink which it sounds as if his probably are.
I'm a little concerned if he hasn't urinated and if he's uncomfortable when you press on his abdomen. Male cats can become blocked and this would be considered a medical emergency. The longer these cats are unable to urinate, then toxins can build up in the bloodstream to the point that this condition can be fatal, unfortunately.
Their kidneys can be permanently damaged as well.
Many of these cats will become lethargic, won't eat and will also vomit. Of course, vomiting bile can also be secondary to an empty stomach so I don't want to over interpret this particular symptom.
In general, I don't worry too much when a cat vomits since it's fairly easy to trigger this reflex in this species; however, when other signs are present, such as in this case, then there may be something else going on.
In addition to a urinary blockage, other possibilities for a cat this age include pancreatitis or a foreign body or viral/bacterial infections.
If there's the slightest possibility that he might be blocked, I wouldn't wait to have him seen if you have an ER hospital in your area. I can provide otc medications which may help reduce his nausea but he'll need veterinary intervention if he's actually obstructed.
I'm sorry that I can't be more positive in my response back to you but this has the potential to be something fairly serious for him:( Deb