Don't use medication on your own without referring the doctor. Take the baby to the doctor and get the right medication. Give the exact dosage as prescribed.
Meanwhile, you can continue to breastfeed or bottle feed your infant as normal, if he takes it.
In case you find signs of dehydration like dry mouth, less than six wet diapers per day, tearless and sunken eyes, a sunken fontanelle, or dry skin, give him an electrolyte solution in between feedings, or replace the feedings with the electrolyte solution. Refer to your doctor before starting.
You can give a sponge bath with lukewarm water to the baby. If you let the water evaporate off his skin, it will help to cool him down.