Hello, Do not worry and try to rinse the area with warm salt water. Avoid extreme temperatures, spicy and acidic foods. Take some anti-inflammatory medication and try a gel with benzocaine to control discomfort. Keep the area clean and give a chance for healing to occur. See your dentist if continues or gets worse. Allow a week, but make sure to schedule a routine dental exam if you are not up to date on your dental visits and report all symptoms to your dentist. Possible causes include trauma such as biting your cheek, hot temperature burn, allergic reaction to food or change in products used. You may have an mouth ulcer. These can be viral, bacterial or fungal. You dentist can best deterime cause with a clinical exam. Thank you for your inquiry. I hope ou feel better soon.