Will cephalexin affect my sprintec birth control? if so when will it be effective again

No, very unlikely: Check out http://goaskalice.columbia.edu/antibiotics-and-birth-control-pill & http://www.mayoclinic.org/healthy-lifestyle/birth-control/in-depth/birth-control-pill/art-20045136?pg=2. Recent studies show that most antibiotics, aside from rifampin, will not affect effectiveness of birth control pills. Just remember to finish your antibiotics - don't save for next infection. And make him wrap it up.