Painful lump on left side of jaw that moves. feels like a cramped muscle. is it a swollen lymph node or something else?

Sub max gland: Most painful lumps under jaw are submaxillary glands in origin. A sone in the duct causes backup of saliva which frequently results in the enlarged gland that becomes secondarily infected. Palpating floor or mouth on the involved side or having X rays to show probable stone required. ENT doc can get films and remove stone if indicated.