Breast Milk going bad

Hi Everyone! Was wondering how long does your refrigerated breast milk stay good for? I’ve been keeping mine for 8 days like one of the breast pump companies says to, however, I took a bottle out that was 8 days old and it smelled sour! I immediately went through the rest of my refrigerated stash and the only ones that didn’t smell sour were the ones I pumped 2 days prior until current day. Is that right? Could my milk only be good for 2 days before turning? Also, I froze milk after 5-8 days of being refrigerated, is that ok or should I be freezing milk right away? If my milk is only good for 2 days my entire stash might have to go in the trash! Oh no, I might just cry if this is true!