Problem freezing cooked chicken

I'm not sure if this goes here but I'm not sure well else to ask the question so here goes. I get chicken breast, cube them and bake them in the oven. I then split it up into different containers so it can cool faster and put it in the fridge to cool all the way down. I then split it again into portion sizes and put it in the freezer. The problem is about after a week it starts to stink really bad and I have to toss part of it out. What am I doing wrong and how can I do it right? This last batch I made was about 12 days so I'm pretty much tossing out a weeks worth of chicken.