I keep getting mouth ulcers at least 2 a week. i've just got one come up under my tongue. why do i keep getting them?

There are a number: of kinds of mouth ulcers although most are self limited and go away by themselves some may be due to infection or Vitamin/Mineral deficiency. You should consult both your Oral medicine provider and your Primary Care Physician.. In the meantime simple MILK OF MAGNESIA on a cotton swab will relieve the discomfor and help heal! Hope this helps! Dr Z