I've had a filling replaced before (silver replaced by silver) and had the same type of sensitivity I'm having now with the two (silver replaced by tooth colored) fillings that were put in a week ago. Like other people, I am having aching and have had to take advil/tylenol daily. I know it was a deep filling on both as well as between the teeth. My dentist took her time, added something to ease sensitivity, and added in layers. Despite the pain, I think she did an excellent job. I'm going in this Friday to adjust the bite, which she actually worked on for a good 20 minutes when I had them put in. Problem is, you can't really tell when you are so numb. The pain from the first replacement did subside after a few weeks, and I'm confident these will too. Just wanted to post to let people know the same problem was there for the silver or the white filling.
Oh, and I have had little or no tooth decay as an adult. I was unfortunately a "propped bottle" child with few dental visits. When I did get treatment about age 13, all my molars needed to be filled. Do the best I can to care for them now, but it is unfortunate that childhood carelessness follows you for a lifetime. Hope everyone is being as careful with their children's teeth as I've been with mine. It is worth the money and effort when they're older!
Hope everyone feels better.