I have been growing in Coco for about 4 years now, and reuse my coco 3-4 times. But each time I treat it with a double dose of some kind of Cyzme product for 7-10 days. I have never had trouble. Mushrooms do not grow unless the spores were brought into the grow room somehow. This could have happened as simple as them getting onto your pant legs while you were outside. Even if I had this happen, after I harvested, I would flush the crap out of the coco with boiling hot water. then flood it with cannyzyme for 7-10 days. Boiling water just kills all the eggs, spores and bacteria and such. which Coco never has when new anyway. Fresh coco every crop is cool, but more costly then I think is needed.
On the Mushrooms, have you got any idea what kind they are? I have never seen mushrooms that smell like you are talking of. But then again there a 1,000's of them out there I would think. I have done a lot of research on how to grow Shrooms, and I have a buddy of my who does grow them. This is one of the things that has me so confused. He has to Sterolize all the items like he is doing brain surgery to get them to propagate, but yet at other times shrooms grow just because. Hell, I used to have an old work truck that had moss and shrooms growing around the edges of the floor boards.
Anyway, good luck on your crop. And never go inside you grow room after you have been outside gardening, hiking in the woods or these kinds of things with out at least changing clothes. But do not go all Howard Hughes on us either.