A 4 year old male is brought to the emergency room with a recent onset of a rash, uicaria, and a fever of 101 degrees F. The mother also states that her son has been complaining that his "bones hu." Physical examination reveals mild lymphadenopathy. The patient's past medical history is unremarkable except that he just finished a 10-day course of cefaclor suspension for treatment of an upper respiratory infection. The patient should be treated with ?