I keep getting ulcers in the same spot in my mouth, and they get pretty big. At the same time, I notice the lymph node on the same side swelling up. This has happened more than a couple of times in the past 6 months. Im worried it could be something serious like mouth cancer, though I know it might sound a bit extreme. How can I find out for sure?

it could be GERD - Don't skip meals, you may not feel like eating but in such conditions you should have the reduced amount in frequent intervals(i.e. 3 square meals broken down to 5 or 6 as you can tolerate) and slowly increase as you get better.- Reduce/ Avoid spicy,fried, fatty, junk and oily food- Avoid/ Limit drinking coffee, tea and carbonated drinks to once a day- Exercise regularly- Increase daily intake of water to 3 liters- Avoid/Stop smoking and drinking if you have the habit- Reduce stress through methods such as yoga/meditation.- Avoid painkillers as it will increase your gastric problems at this moment.