Question for someone who knows about bacteria?

PLEASE take this question seriously and maturely!! I was bulimic a while ago. (Not anymore!) But when I was, I would take an old shirt and gag myself with it, forcing myself to throw up. I would take the vomit-covered shirt, put it in a plastic shopping bag, tie it up, and kind of just throw it into my walk in closet. This happened more than once... And I was too scared to put it in the garbage, in fear of my parents' reactions if they were to find it. Anyway, I noticed that after a week or so, the clothes started to smell of mold, and they had mold ON them. Also, A LOT of small fly-like insects were coming out of the bags..So my question is: Were the flies already in the house, and were attracted to the mold? Or were they somehow produced by the mold? btw, I threw all of the bags away in our large garbage bin outside on garbage day!