If the milk came straight from you, the milk is fine. Milk can't sour when in your breasts. The change probably came from your diet and it's really nothing to worry about, it still has all of the same wonderful bennefits that all breast milk does. Your baby, however, may reject the strange taste, if (s)he does then put him/her to the breast so (s)he can see that what they are getting from the bottle is, indeed breast milk. Your baby probably is used to this occasional flavor variation and won't be phased.
at 10:37 PM on Feb. 8, 2010