If you're going crazy, so am I - it's not constant, but I certainly seem to be a lot more sensitive to sewage smells post-op than I was before. Some other smells too: I had some rugrats over and for a week afterwards, I'd suddenly get a whiff of berry tube yogurt. My sister later told me one of the kids had spilled a little on a couch and she'd cleaned it up, which I'm sure she did, since I'm the only one in the entire family who keeps smelling it. I'm also pretty sure one of my perfumes has turned, though no one else thinks it has.
So maybe it's just a sharper sense of smell?