Redness with small pimples inside the mouth is often due to minor infection, irritation, vitamin deficiency, or stress affecting the oral lining. Rinse with warm saltwater, maintain good oral hygiene, drink enough fluids, and avoid spicy or hot foods to aid healing. Eat nutritious food, especially foods rich in vitamins, and avoid biting or irritating the area. If it does not improve, becomes painful, or keeps coming back, consult a doctor to check the cause and guide proper treatment.