Mouth sores even when brushing teeth

At first, I didn't know why my mouth kept getting sores. Even after seeing a doctor, it was the same. They'd heal and then break out again, repeating the cycle. I wondered if it was due to internal heat, or staying up late, or being 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!