A 46 year-old male developed a hard, painful swelling with redness and discoloration on his right shoulder. He reports 10 hours ago he received a tetanus vaccine on the site where it is hurting now. He reports that if his memory is right, his last tetanus vaccine was 3 years ago in the same site after he accidentally stepped on a nail. But he is not sure because he does not keep a record of his vaccinations. As you consider this reaction to the tetanus vaccine, what would be the best advice to give to this patient?
