From what I've read, I realize you can't spread canker sore to another person, but do you know if they will spread in your own mouth? Here's my deal... I was putting gum in my mouth taking one bite at a time and I bit the inside of my lip. HARD. So hard I could hear it CRUNCH! It was just awful, and because it was swollen... I bit it AGAIN. OUCH! It actually hurts worse now than when I bit it 5 days ago. Now I have a sore on the inside of my cheek and on the side of my tongue. Just wondering if maybe that canker sore spread, or is it just coincidence.

Stress, anemia, and a genetic predisposition may cause a person to get them. If you eat the acidic foods or irritate the inside of your cheeks in some way, the sores can appear.

I dab them with a cotton ball soaked with alcohol or apply alum with a Q-Tip, both treatments will dry hem up.

Canker sores are caused by a virus and cannot spread from one person to another but you can get many in your mouth at one time.

Okay thanks for the answers... Just a reminder though. This sore is from me biting the crap out of myself... twice.

Canker sores are caused by a virus and cannot spread from one person to another but you can get many in your mouth at one time.
No, Flossie. Cold sores are caused by a virus, but canker sores are not.

From saveyoursmile.com --

Q: What causes canker sores?

A: It is not known exactly what causes canker sores. This is an active area of research. Current theories point to canker sores being the result of a localized autoimmune disorder. It is thought that the body's own immune cells attack the cells lining the inside of the mouth.

While the immune dysfunction is thought to be the underlying mechanism of canker sore formation, it is believed that certain factors may initiate the chain of events leading to canker sore formation. These factors include sensitivity to certain foods, certain ingredients in toothpaste, stress, and trauma to the lining of the mouth.

I also agree that they are not caused by a virus.

Viruses may play a role in canker sore formation by way of causing an immune response. Some of the strains of viruses whose presence has been associated with aphthous ulcers are: cytomegalovirus (CMV), human papilloma virus (HPV), human herpes virus-8 (HHV-8), Epstein-Barr virus (EBV), human immunodeficiency virus (HIV) and herpes simplex virus (HSV-1).