Your toddler must be having a bout of viral infection and is known as Hand, foot and mouth disease. It is a self-limiting condition that normally settles within 7 days. To relieve the pain you can use paracetamol syp 5 ml twice a day after food for a week. The most common type of virus responsible for this condition is cox sackie virus A16 or Enterovirus 71.This condition is highly contagious for a week. Usually spreads after coughing or sneezing or inhalation. Hence proper hand washing is advised after using the toilets. This condition is usually seen in nurseries or child care centers. I would advise you to hydrate the child adequately and if the child develops fever then you start the antibiotics after consultation with the pediatrician.