Drooling normally indicates pain and/or an upset stomach. There are two things that immediately come to mind considering you gave him a pork bone..one is pancreatitis and the other is a possible obstruction. If he is eating and able to hold food down, I would lean towards pancreatitis. BUT if he is vomiting and has runny stool OR constipation, along with abdominal pain, then an obstruction is possible. Considering we are coming up on a weekend, I would really consider having a quick x-ray done to rule out the obstruction. For now, try a bland diet of boiled chicken and rice and make sure you keep him hydrated. You can use some plain pedialyte in his water. (if it is pancreatitis, this will help settle the tummy and so go away in a couple of days)
I would not recommend pork bones of any kind for any type of dog. Instead, consider a safe chew like a bully stick. These can be purchased at major pet retailors and can provide hours of safe chew time per stick..and they are all natural :)
Let me know if you need any further information.
Chance are pretty slim its from teething and I've never heard of a problem with doggy litter. Dogs that eat cat litter, usually when its clay based, may have problems with obstructions but I doubt its from the paper litter. The best bet is from the ham bone. If it was a bone from your dinner, the fat content is very high and ham bones in general spliter. Considering he is still eating, I am not overly concerned with an obstruction but if he shows symptoms of vomiting, diarrhea with or without blood, constipation, lethargy or fever over 103 along with refusal to eat and drink, definitely get him in ASAP. But the boiled chicken and rice throughout the weekend should settle his tummy. :)