Though photo is not clear need a better quality photo to see the ulcer, All ulcer should go for physical examination to palpate the base of ulcer  ,..and neck lymph nodes area. Many times vitamin deficiency/ stress can cause apthous ulcer. Note any sharp tooth they are danger Tobacco and tobacco related product should be stopped if using. Few projections that are seen they are taste buds circumvallete papillae but they are larger on left side..

It appears to be a case of aphthous stomatitis or non specific stomatitis. Advised: beta dine mouth wash , mucopain or lexanox plus mouth paint application, B complex , vitamin C and paracetamol tab