Having just read through this I must say the OP has had a rough road and kudos to him for his continued efforts. I am thinking as others above that this could be environmental.
If you have any sort of Air conditioning system in your house it could well be the cause. I remember reading a blog of a brew store and that was where it was eventually traced. What he did from that point was to fully enclose ALL wort transfers, any container that was to have wort transferred to it was first flooded with co2 then starsan type sanitizer. It apparently worked well. Obviously you would still need to oxygenate your wort for fermentation, but a fully enclosed process is possible. I read this some time ago so unfortunately I can't remember where as I think a link to his method may be of help