If there is a small lump or sore beneath the tongue, it might be a canker sore or clogged salivary gland. You can get these if you accidentally bite your tongue or eat something hard. To lessen the pain, try rinsing with warm salty water and avoid hot, spicy, or acidic food. If it persists beyond one week or worsens anytime before then, it’d be wise to seek advice from a dentist.