You can keep ya ebm in the fridge dor 3-5days. It was recommended to use it within 3 days for freshness of the BM. After 4 days, maybe you would like to smell or taste it first on whetehr it has turn sour. If you kept it at the back of the fridge maybe still ok. But still good to check 1st. If turn sour cannot consume but u can still use it for milk bath or milk facial mask=) You can read up the link below and take a look at the picture which I took it from Audrey Wong from TLO. http://www.babycenter.com/404_how-long-does-breast-milk-stay-fresh_8918.bc
According to this website, freshly expressed breast milk can be stored in the back of the refrigerator for up to 5 days in clean conditions. However, use or freezer storage of the chilled milk within 3 days is optimal. http://www.mayoclinic.org/healthy-lifestyle/infant-and-toddler-health/in-depth/breast-milk-storage/art-20046350?pg=2
You should have left it in the freezer from the beginning. Nonetheless, give it to your baby 1st to finish up instead of wasting it. Our breast milk is Liquid Gold ... Please don't waste it.
Smell the milk . If it smell not right , pls discard it .