My 18 month old was blue and not breathing when I woke up! Docs say not SIDS. Please read more.?

She has no family history of any such thing on either side. I can't tell you how awful this is. So far we've done an MRI, EKG, and an EEG. All were normal. There was a small amt of Carbon Monoxide found in her blood and while this was no concern to the doctors who were certain it was nothing to worry over, I immediately had the Gas company test our home and they found next to nothing. The man's meter said 1. (uming parts per million) he was also not concerned about that amount. We do have chain smoking neighbors and he found a 5 in their place, our town homes are connected. I'm afraid to sleep at night for something happening to her and not catching it. Please offer any experience, or relative suggestions, especially if your a doctor. Thanks.