I was using arm&hammer advance white toothpaste &now i think have a cold sore on the corner of my mouth and maybe a pimple on my lip? how do i fix it?

Toothpaste?: Could be from toothpaste but is unusual. Do you think you might have been exposed to herpes simplex virus. Kissed a boy with a cold sore recently? Or do you have history of cold sores . Dr can prescribe Valtrex (valacyclovir) or you can buy abreva lip sore treatment over the counter. Don't squeeze pimple or anything on lips, since that will create greater infection.

Prevention: Canker sore or more specifically aphthous ulcer can be prevented by avoiding a common foam detergent found in most toothpastes called sodium laurel sulfate. Switching to biotene or other toothpaste not containing this ingredient can be the cure in preventing this painful condition.