I'm getting deep pain at times from a tooth or gums around left side of jaw. saw my dentist and he said pain is not from a tooth. what could be cause?

IDK: The dentist who actually examined you should be able to give you better answers than dentists on this site that can neither personally examine you, see x-rays of the area or perform a number of tests. If you can't get the answers you want from your existing dentist, consider getting a second opinion.

Second opinion: It may help you to know that it's common for patients to get a second opinion, and most doctors are comfortable with the request. See an endodontist for a second opinion.