Hello. Thank you. Chain of events. Will try to be concise. Had rash, dermatologist gave me Hydroxyzine. Cleared rash, got diarrhea. Persistent. This occurred about a three weeks ago. Developed sore throat, which aggravated a recent root canal, and dentist says I may have an abscess in neighboring tooth. Prescribed penicillin. I think he fears an infection. On it for one day now. Tooth throbs. I am concerned this may make my make my diarrhea worse. I am scheduled to see a doctor tomorrow. Should I be taking a different antibiotic? Is it possible the root canal didn't get all of the infection? I know I need to see a doctor, but I am looking for a short term course of action until that time. Thanks again.