Omnicef and reccommended

My 27 month old son took Omnicef for 8 days for an ear infection. Good news: the infection cleared up...Bad news: He has welts all over his abdomen, as well as some on his ears, head, and legs. We returned to the doctor, and he said that it looked like an allergic reaction, but did not seem to tie it to the Omnicef. We went ahead and stopped administering it anyway. He reccommended Benydryl. Today I talked to the pharmacist, and she reccommended a Cortaid spray, that would help heal from the outside while the Benedryl helped with the reaction. After reading this site, I am worried that this could go on for weeks.