First You need to visit the dentist for the clinical evaluation . Second ulcers can occur due to many other causes and we need the find the reason behind that . Any deleterious habit can also lead to ulcers. But for mean while you  can use dolo gel  (apply over the affected area ) Cap. BNC daily Tab. bifilac twice daily Local application of metrogyl gel Add fibers to you diet

You can apply anaesthetic ointments like dologel CT for temporary symptomatic relief till these legions heal within 7 to 10 days. Regards

You are suffering from apthus ulcers ..reasons may be stress indigestion idiopathic start tab becosule tablet Kanacort ointment for local application