Hi. What you are experiencing fits the description of a condition known as Burning Mouth Syndrome or BMS and it occurs most commonly in middle-aged or older women. Moderate to severe burning in the mouth is the main symptom of BMS and can start suddenly for no apparent reason and sometimes persist for months or years. The most common cause for BMS is if there is damage to nerves that control pain and taste. As age progresses, the nerves supplying the cheek tend to lose their protective covering and start to misfire normal signals in the form of burning sensations. This is called as neuropathic pain (Burning, sore feeling). Many factors either individually or in combination can lead to this damage to the nerves such as hormonal changes due to menopause or dry mouth, which can be caused by many medicines, hormonal changes and disorders such as Sjögren’s syndrome or diabetes. Nutritional deficiencies especially vitamin B1,B2 and B12 can cause nerve damage and delay their healing. Some of the other less common causes are oral candidiasis, a fungal infection in the mouth, acid reflux, poorly-fitting dentures or allergies to denture materials, anxiety and depression. You will require to see an ENT or a dentist/oral pathologist for a thorough oral cavity examination along with blood/swab tests to rule out many of the causes mentioned above. If a direct cause is identified then it can be treated easily. For the time being, I would recommend a multivitamin capsule (Vitamin B complex and vitamin C) once daily after meals for about 3 months. Sip water frequently and maybe suck on ice chips once or twice a day. Avoid irritating substances like hot, spicy foods; mouthwashes that contain alcohol; and products high in acid, like citrus fruits and juices. Brush your teeth/dentures with baking soda and water. Avoid alcohol and tobacco products. It doesn t look likely that your surgery in 1989 has anything to do with your symptoms. Hope this information has helped answer your question. Please feel free to ask me anything else if I have missed to address in this response.