Hi, I started clarithromycin yesterday evening & took one 500mg tablet & have taken another 50mg tablet tonight . My Dr prescribed a 7 day course for breast pain & under arm pain & jaw & neck pain. I also may have cystitis or uti as running to toilet a lot. I m not sure if i ve a tooth infection also. I do not feel a bit well...& burning up & feel sick. Do you think the clarithromycin isn t agreeing with me?