question: I have been going to my dentist for ortho care: 6 month smile braces.  This weekend I have been having on/off pain on my left jaw.  I visited my dentist and she wants to inject my with Arestin, local antibiotic.  My pain is not localized.  She would not prescribe an oral antibiotic.  I have Keflex at home, can I start using it?  Arestin is for bacterial infection, but I feel I need a general antibiotic, not a localized one that is very expensive, and not covered by by insurance.  She wants to start doing 2 at a time. Please, guide me.