Long stranding ulcers are not that good and need to addressed. Symptoms may include hardening of sides , elevation of sides , bleeding , difficulty in mouth opening are some of the symptoms that could be seen . You can get it examined by a doctor , and if needed can go for biopsy .But don’t worry as there are many other causes which can cause ulcerations , lasting for this many days , so don’t worry just need to treat it properly . If you want any detailed advise from my side you can consult with photos or videos of the ulceration and detailed history of your symptoms .