It is quite common for babies to have pain, mild swelling, or hardness at the injection site after vaccination, and this can make them irritable or cry. You can give Calpol Paediatric Oral Suspension for pain and fever, but only in the correct dose based on your baby's weight; so it is best to confirm the exact dose with your paediatrician. You can also apply a cold compress gently at the injection site and keep the baby comfortable. This reaction usually settles within 1-2 days. However, if your baby develops a high fever, excessive crying, increasing swelling, seek medical advice promptly.