Mammo is right , and also canker soars can appear when you are stressed out, immune system is down. Don't sleep one night, not
only you'll get canker soars, a cold , and herpes
can show up too. In your case, herpes is not in your body, at least you don't have to be worried about that. Also check for a sharpness on a tooth, a filling , or a crown , that can at times hurt your tongue, and then cause a canker in some people , since you said it appears in the same spot.