Depo shot and antibiotics?

ok so i started a Zpack on tuesday for a slight case of bronchitis. since then i've gotten a full blown period almost immediately after i took the pill... does this mean my depo is uneffective? i looked on drugs.com where you can see if pills have effects and i didn't see zythromax on there... if it did make it uneffective.. do i have to wait til my next shot for it to work again or does it work again after 10 days? (3 day pill, 10 day effectiveness)