16 months baby toenails yellow, will hurt, may be nail ringworm, under the nail bleeding and other factors caused. 1. Ringworm of the nails: ringworm of the nails is caused by fungal infection. If the baby has direct or indirect contact with the patient with fungal infection, it may induce fungal infection, leading to nail plate deformation, discoloration, thickening and peeling, which may cause redness, swelling and pain. 2. Bleeding under the nail: the nail is subjected to external forces, bleeding under the nail, the color of the nail may be yellow during the recovery period, and the pain will be accompanied by pressing with the hand. It is recommended to choose the right shoes for the baby, if necessary, go to the hospital dermatology department to find out whether it is related to fungal infection, but also combined with the doctor’s advice to give medication.