Canker sores in the oral cavity indicate that you are probably experiencing some kind of mouth inflammation (stomatitis aftosa). Infection is one of the possible causes for stomatitis. But even if something else caused the inflammation, infection is often secondarily present because the oral cavity is not sterile but always full with microbes that can cause a secondary infection and worsen a primary condition. That’s why you can use some local antiseptic (1% iodine solution for example) to treat the symtpoms, no matter the cause. You can then consult a dentist about your condition.