it can be a case of glossitis
take bland diet,glycerin borax apply thrice daily, vitamin B complex forte tab 2 daily or inj.B comlex with B 12 1 ml IM daily for 10 days, avoid spices ,tobacco hot foods, smoking and alcohol.
take some systemic antibiotics to prevent secondary infection, if pain take paracetamol
tds, zytee or mucopain.
if not relieved within 3 weeks then go to an ent surgeon to rule out herpes labialis, oral thrush
and go for biopsy of the lesion to rule out any malignancy.