Frozen milk

My son does not take a bottle at all I have tried 6 different bottles with no luck. So I decided I would use my frozen milk for his cereal. I thawed some milk and smelled it and it just smelled different. I decided to taste it because I didn’t want to give it to him if it was bad. It left a bad taste in my mouth. I took out my most recently frozen milk and it’s the same. Had this happened to anyone else? Should I just dump my frozen milk? How do I tell if it’s all bad?