Pain on both walls of the mouth may be caused by trauma, ulcers, herpes, mucosal fibrosis, parotid duct stones, etc. It is recommended to go to the hospital for specific examination and treatment. 1. Long wisdom teeth teeth position deviation, residual roots, residual crowns or eating inadvertently bite, may lead to mucous membranes appear local trauma with pain. 2. Due to vitamin deficiency or healing period after trauma, etc., ulcers may appear and be painful. 3. Intestinal virus infection, herpes virus infection, etc. may cause blistering of the mucous membrane in the mouth and burning pain. 4. Frequent chewing of betel nut or smoking may result in fibrosis of the mucous membranes, and there may be scar-like striations, blisters, and ulcers in the mouth.