Y.V.
M.:
I had a similar problem, my breastmilk tasted/smelled soapy and metallic. It was because I had extra lipase in my bm. It's actually pretty common but at the same time not a lot of bfing moms know about this, or even doctors. A good lactation consultant should know about it. Go to the LLL boards and search excessive lipase and you'll find tons of great info.Google it as well. Good thing is that the milk is not really spoiled, some babies won't like the taste but others don't care.
I had a "milk lab" in my kitchen. I saved 1 oz milk samples and tasted it everyday to find out when it started tasting funny:) In order to inactivate the lipase you have to scald the milk before freezing it. I did it for the longest time, until eventually my milk started tasting/smelling fine. Sometimes as the baby grows and milk changes composition the lipase issue resolves.
Good luck!!