Dark spot on gums under tooth where chewing tobacco is usually put? what could it be? the tooth does have some gum recession

See the dentist: Hard to say, chewing tobacco has been shown to cause cancer of the mouth. You definitely need to get this taken care of ASAP and see an oral surgeon for a possible biopsy. This could turn out to be just a simple thickening of the tissue or an irritation.

Examination: Carcinogens in the tobacco can cause changes in your soft tissues, and this is something that needs to be physically evaluated. No guessing allowed.