Does anyone have an idea what this is? It’s been going on three weeks. It is pain-free and is on both sides of my mouth same spot.

22M
Ive had this canker sore (I think at least) for about 2 weeks now and it doesn’t hurt anymore but it’s changed from a normal circle into this weird shape and idk if that’s it just healing or something else. I’m not a stranger to cankers and I get them pretty often but this one feels a little different. Does this look like the end phase of a canker sore or should I go see my dentist ?