Hello from JA
My name is Woody.
I will be glad to assist you today.
I have been servicing ALL Major Brands of Appliances for 35 Years,
and have over 100,000 in home repairs and over 80,000 internet repairs under my belt.
This is a issue with the quality of your water that is supplied to the refrigerator.
And your not going to like what I have to tell you ,
To get rid of the odor you will have to replace all of the plastic tubing and water reservoir in the unit .
BUT how ever old the unit is it will take that long for it to return .
So if it is 18 months old in 18 months it will return .
You can replace all the plastic tubing and water reservoir ,and install a water osmosis system that will remove 100% of all the minerals in the water out but they are several hundred dollars.
This is a very common issue in the southern states with high calcium content in the water.
If you have any questions just reply back .