Mouth sores from brushing my teeth

At first, I didn't know why my mouth kept getting sores. Going to the doctor didn't help either. It would heal and then break out again, repeating over and over. I wondered if it was due to 'heatiness' (internal heat), or if it was because I was staying up late or too tired. I changed my habits, but nothing improved. Then one day, I ran out of my usual toothpaste and bought a different brand. After I started using it, everything got better. I have boards called 'Travel Matters' and 'Life Matters'. Share your travel and life stories with me!