Hello doctor around one and a half month, I got developed a severe painful chronic non healing mouth ulcer and it could not go away. I have a doctor friend who consulted me some antibiotics, pain killers and ointment to heal the ulcer. It was an online consultation but as it is, the ulcer could not heal. And suddenly two days ago, I got realized that I used to have a medicine called isotroin 20 capsule for the oily skin (face) which was prescribed by dermatologist. Then I searched the content of that drug and it's context with my mouth ulcer and I got to know that because of the isotretinoin and it's properties I used to have a very dry mouth and got some bacterial infection and fungus in mouth and developed an ulcer and reduced calcium and vitamins level in my body. I think, I have vitamin b12 and b9 deficiency and due to this developed an ulcer. So should I go for the biopsy or not? And what vitamins and calciums should I take and also read that in these type of cases one can have ample amount of vitamin dosages to heal this.