Sorry to hear about your trying experience. How does ds react to the bottle? Do you think maybe he has become a little lazy over the past few months, know that anytime he has trouble or doesn't nurse well he will get the faster flow bottle?
If you think this might be the case, let us know. There are other ways you can feed him EBM while he is on a nursing strike.
That being said, has he been ill at all? Have you had him checked just to make sure he has not had an ear infection, sore throat, etc?
Also, have you considered that he might be reacting to something in your diet? Babies are so smart. They know what is causing them discomfort...even if it is the same thing GIVING them comfort!