I remember that same experience after my wisdom teeth were removed - a long time ago. I also remember that I tried holding and wiggling the tooth causing pain and noticed a little click that felt like the tooth had snapped back into a better and more original position. After that the pain on biting down was gone. My theory was that the second molar had been knocked ever so slightly out of perfect alignment from the removal of the wisdom tooth just behind it. Once it was settled back into the proper place (very tiny movement) but enough for me to be aware of, everything felt better.