Many years ago, I was in a research study with the Medical College of Georgia Dental School. I had terrible mouth sores that would last for weeks. They gave me a tube of something, I used it, and the sores immediately cleared up within a few days.
When the study was over, I asked what it was. It's Clear Red Close-Up toothpaste. When I get a sore, I dab some toothpaste on the sore with a Q-Tip every time I feel pain. It takes away the pain much better than Ambusol. I brush my teeth with the Close-up toothpaste until the sore is gone. Now my sores last 2-3 days. I have recommended this to so many people over the years, and it has worked for everybody. I get my toothpaste at Walmart- it's about $3 for a big tube- and it lasts a long time. If your kids get sores, you can send the toothpaste to school with them- it's not a medicine, it's toothpaste. I've been using it now for 35 years and it has never let me down once.