My 18 year old daughter just returned from ER for bronchitis and a very bad headache, chest pain from coughing and fever and chills. Among other drugs, he gave her one oxycodone pill which, after four hours, and now ifs home, she is feeling agitated. I thought the ER doc said if she developed this symptom, taking an antihistamine would help. She is allergic to Benadryl. If an antihistamine would help, what other ones would you suggest? Thanks.