I started to have tooth pain this week, went to the dentist on Saturday and he said I need a root canal! This was a TOTAL shock to me as the tooth just started bothering me a few days ago. Anyway this is a new dentist, and I am worried that he is wrong about needing a root canal He gave me Keflex (Cephalexin) Antibiotic and I am so sick from them, even though I have taken them b4. Stomache pain, total fatigue, upset stomache I don't know what to do. I am not sure this doctor diagnosed me right. Besides probiotics (which I am afraid of for some reason) what else can I do? Has anyone in the past taken a different antibiotic (besides Penicillen) for tooth problems?