pinning down infection

So over my last 5 batches, I've had this infection. Its got a medicinal smell/taste, 3 of them it overpowered the beer and was just terrible, 2 of them it was there but not as bad. I've ruled out yeast (used dry yeast from packet, wyeast propagated, white labs direct pitch from the tube, all fermented at about 63-68F). I've mostly ruled out water (put a carbon filter on the faucet after the first batch after thinking it was chlorine in the water, used gypsum in one batch and 5.2 buffer in another). I don't use chlorine to clean, I use PBW with a good rinse, and a deep soak in star sans. I've replaced all my plastic, save my better bottle fermentors (two batches were fermented in glass carboys so it's not just the plastic).

The last thing I can think of is my Immersion chiller. Its the only thing post-boil that hasn't been replaced. I'm wondering if its 1 of 2 things. Awhile ago, I did soak my copper chiller in an overnight bleach bath in my stainless kettle (I know now bleach + stainless = dumb). I rinsed it thoroughly, but I wonder if the bleach might have reacted with the copper or stainless and is having some reaction it keeps carrying into my wort. Second, does a boil sterilize or just sanitize? If I do have a wild yeast infection, wouldn't a boil kill all of it if its in my boil kettle/immersion chiller?

Normally I don't use bleach to clean, I just ran out of PBW without realizing it so I used bleach to clean up after brewday

The only technique change from the 40 or so beers I did before that never had a problem was I started skipping secondary, and just leaving in the primary for a month, but I can't really believe that would cause this problem.