Post vaccination swelling may be a common thing specially after DPT vaccine which may be painful for two or three days and the swelling may remain even up to month so if it is not causing any pain or other symptoms nothing to worry. Swelling can be reduced by giving ice fomentation locally and paracetamol can be given for fever or pain. Thrombophobe ointment can be applied in acute pain and swelling .

Ice pack fomentation with cloth over injection site superficial aproach to follow . If it still persist then have a teleconsultation with Paediatrician.