I would recommend seeing an oral surgeon for a proper diagnosis of the area. If it is indeed a swollen salivary gland, its possible that it is blocked but something and its causing a buildup of saliva in your gland. This is usually irritated by eating (since you create more saliva when you're about to eat) and can cause more swelling and buildup in the gland since it can't escape. Usually a little surgery to open up the duct leading to the gland can fix the problem.
I don't imagine that the blockage of a salivary gland has anything to do with your fillings.
Let me know how it goes. Hope that helps.