I'll be taking the rx clindamycin for a tooth/gum infection. what is the best way to avoid the diarrhea and stomach upset from this (yogurt?)?

Good probiotics &...: Clindmycin is an excellent choice for dental infections. While there is some risk of C.dificile, other antibiotics can cause that as well. I advise you take Sacchromyces boulaardi (sold as Florastor) and Culturelle, both widely available in pharmacies, both during and for 2 weeks after your Clindamycin. Also avoid sugar and simple starches while taking antibiotics as well.