Use zytee gel before food ,tab. Becosules once a day for 2 weeks .

This looks like an aphthous ulcer. It appears in times of stress or unhealthy diet. It may also appear if some food does not suit you. It will disappear spontaneously in about 10days. Till then, please apply benzocaine or zytee gel  to the ulcer before meals. This reduces the pain and allows you to have proper meals. Try to  have a diet rich in green leafy vegetables and colored fruits like mango and papaya. Such ulcers tend to recur in some people. The predisposing factors have to be taken care of.