[Ashleee:)]

you could try going to your dentist, if its not that sore it may just be a cut in your mouth which has formed in the shape of an ulcer and may be caused by overhangs of fillings in your mouth, or from the biting surfaces of your teeth being jaggy. Any sore patches, lumps or ulcers in your mouth which last for longer than 2weeks should def get seen to by a dentist