Hi... For Ten Days Now I Have Intermittent Throbbing Pain

Hi... for ten days now I have intermittent throbbing pain in my lower farthest molar. Saw my dentist who filled a small cavity in that tooth last Wed. He saw no reason for the pain and suggested more stress as the probably cause. have no sinus issues, or cold. I did start wearing my mouth guard, that he had repaired, 10 days ago, which I suspect might be the culprit. Much of the time other teeth are hurting also. The main tooth is sensitive to eating, hot and cold. I'm 75 and in good health.