soreness at the injection site is probably the most common adverse effect especially with the dtap. often this is not just due to vaccine but the trauma of the needle and some bleeding into the tissue (usually this is the cause of the "knot"). warm compresses may help as well as some ibuprofen for the inflammation. if it becomes red and more swollen you will need to see your medical provider to see if you have a injection site infection.
got dtap vaccine week ago. injection area is swollen and has knot gets sorer every day. is this normal?