What could be causing a electrical sharp pain in just one tooth after eating sweets? it happens a few days a week then goes away and comes back?

Pain in tooth: A pain in a tooth in response to eating sweets has several possible causes: decay, a cracked filling, a cracked tooth, a periodontal (gum) infection, gum recession with root exposure, etc. See your dentist for x-rays and an examination.

Sweet sensitivity: eating sweets produces acid in the saliva . if there is an unprotected spot on a tooth(either the root surface, where there is a leaky filling, or possibly infiltration of new decay), the saliva penetrates that surface and then, because there is a difference in ions, an electrical reaction occurs that elicits the sharp pain. your tooth adapts, then rxn repeats