I googled foot cellulitis. O. M. G. One can only hope some of the photos were of dead people! It said you might need ten days to two weeks of antibiotics. And to NOT expect it to get better on its own. Does keflex keep working like zithromycin does? A z-pack you take for 5 days, but its supposed to keep working for a few more days. If you think you need to go back to urgent care, just do it. keep us posted.