See below. If antibiotics like Keflex are not helping i would think about having the tooth extracted. Keflex is a strong wide ranging antibiotic and usually works...If the tooth is abcessed and broken you probably will need root canal therapy if you can get rid of the infection. As i said i would have thias extracted.
See a dentist ASAP. An antibiotic may simmer things down, but you should see a dentist to determine the source of the tooth ache, and not take antibiotics which may mask and only treat some of the symptoms.
A few alternatives.. I have found that in my experience, I have better results with amoxicillin, augmentin, (amoxicillin and clavulanate) and clindamycin. Both Amoxicillin and Augmentin (amoxicillin and clavulanate) cannot be taken by someone allergic to penicillins. Also, those prone to intestinal problems should be careful taking clindamycin.
Antibiotics/abcess. The answer is any antibiotics are just a temporary fix. You need to see a dentist to address the broken tooth and the abcess. Keflex is a broad spectrum antibotic. It is meant to address many different types of bacteria. However, it may not not treat all types of bacteria, or some of the bacteria may be resistant to the Keflex if you have taken it many times. I would suggest see your dentist.Asap.
None will work. Antibiotics are rarely helpful for abscesses. Abscesses are pockets of infection that generally required drainage and/or removal of the broken tooth.