Sore lik a burn inside mouth?

Mouth sores. Certain medications, for example methotrexate, can cause canker sores as well as deficiencies in some b vitamins (1, 2, 6, and 12), iron, folic acid, and zinc. However, irritation, injury, or infection of any of the tissues in the oral cavity can also lead to mouth sores. Sores in the mouth can occur with certain systemic disease like crohns, behcets, or lupus or viral infections. See doctor.