im pretty certain it has nothing to do with steroid use. i got the ammonia smell without using steroids..
it probably happened because you changed your diet (knowingly, or unknowingly) when you started your cycle. your protein intake went up, while your carb intake probably got too low.
once those shirts get stained with the smell, there is no hope getting the smell out. as soon as you sweat one drop on to the material, you reak like javex. just chuck the shirts out, and try to eat more carbs, and drink more water.