My son is 4 months 10 days old and weighs around 6.5 kgs. He got vaccinated 3 days ago, 3rd dose of easy 6 vaccine (usually given to babies at 6, 10 and 14 weeks). His thigh is swollen, hard and red at the injection site. It's been 3 days since he was vaccinated. He doesn't have a fever or pain if we touch the injection site. Is it a side effect of the vaccine? This has not happened before during the first two doses. Doctor has recommended 3 ml of ibugesic syrup for 2 days, twice a day. Is this something to worry about? And is ibugesic syrup ok for a 4 months old baby?