I have what appear to be canker sores from time to time. Where did these come from? Is there anything that prevents them, or eases the discomfort when they do appear? There does seem to be a stress factor.
You have that last part right. Stress does seem to play a role in deciding when these little ulcers in the mouth will make their painful appearance.
In most cases, we believe that common ulcers cause these troublesome sores. A vitamin deficiency and stress can make outbreaks more common. Beyond that, we do not know a lot about what causes canker sores, known medically as aphthous ulcers. That makes canker sores hard to prevent, other than avoiding known triggers, such as stress. It may be worthwhile to take a daily vitamin/mineral tablet.
Canker sores can last up to 10 days, peaking for three or four. It is not a serious condition in the sense of causing lasting bodily harm. But canker sores can cause horrible pain and discomfort, especially if you eat acidic, spicy or heavily salted foods.
For pain relief, you can rinse your mouth with a solution of two parts water to one part hydrogen peroxide. There are non-prescription oral anesthetics that help, too. Or talk with your doctor about other options. Sometimes the antibiotic tetracycline is prescribed for use as a mouth rinse.