Like Torben's said, it definitely sounds like teething.
Unfortunately, there's no way to 'speed' it up - until the teeth bud and erupt, your son is going to drool, gnaw and put anything he can in his mouth to alleviate the itching/burning sensation in there.
I've also never heard of calcium supplements for teething, and would also recommend a talk with your doctor; adding extra calcium to his diet might effect his iron levels negatively.
Pieces of fruit from the 'fridge were a hit with my son, as were carrot sticks. They were large enough that he could hold them and gnaw on, but not choke upon.
Another option is a clean cloth diaper - soak it in water and tie a small knot in the middle, then place it in the freezer for a half hour to an hour. It's another texture he can experiment on, but not injure himself with.