New Delhi, April 29 -- One in five people get recurrent mouth ulcers - small painful sores. You might get them on the inside of your lips, the insides of your cheeks, the base of your gums, or under your tongue. These small blister-like sores are quite different from fever blisters, which usually appear on the outside of your lips or the corners of the mouth. Mouth ulcers usually pop up alone, but may also show up in small clusters....