Canker Sores: What to do
Canker sores are not fun to have. They are also called aphthous ulcers and they can be very painful and downright irritating as they will make eating food and brushing your teeth difficult. Canker sores look like white-pinkish splotches on the inside of your mouth. They can occur on the insides of your lips, cheeks, and even tongues. It's not clear what causes them. There are some indications that stress may be a factor as well as hormones and diet. In any case, they are not the same as cold sores which are contagious and usually appears to occur outside of the mouth. Unlike cold sores, canker sores are also not contagious. So, no worries over infections.
Partly since there is no clear reason for why canker sores occur, there is also no clear treatment (i.e., as in treating a sore caused by bacteria or a virus as in the case of cold sores. If left alone, canker sores usually go away within 1-2 weeks.
If possible, keep the sore wet or lubricated so that it does not become worse. If you sleep with your mouth open, chances are the sore will become dry. When that happens, it feels like the sore has been further aggravated when you wake up, kind of like when a leaf dries and easily cracks. Therefore, if possible, try to sleep with your mouth closed.
Similarly, try not to aggravate the sore by overtly touching it with a toothbrush or certain kinds of foods (e.g., spicy, tart, etc. foods). These will not only cause pain but could very well make the sore worse, and take longer to heal.
Use something to cover the sore to help it heal. While you are sleeping, perhaps the simplest thing to do would be to use some petroleum jelly (e.g., vaseline). First, use a towel or tissue to dry the sore. Then using a q-tip or even your finger, apply a generous amount of the petroleum jelly so that all of the sore is fully covered. This will not only help the sore to heal faster but should provide some pain relief as well. There are various over-the-counter medicine that can be used and homemade peroxide-based mouthwashes that can be used. Rather than going through all of that, simply make sure your mouth is clean (i.e., carefully brush your teeth) and then apply some petroleum jelly to the sore. It is the simplest thing to do and is very effective.