Help! Sour beer!

I see that there have been some threads about this topic in the past, but I've yet to find a diagnosis and some agreed upon suggestions. Here is the situation:

I brewed a Scotch Ale a few weeks ago. After an appropriate time in the primary, I racked to a (well-sanitized) carboy two days ago for clarifying (the stuff was still very murky). I used some neutral Knox as a fining agent (you know the drill). I just noticed some small patches of bubbles forming on top of the wort. I removed the airlock to get a whiff and...UGH. Extremely sour, vinegar like smell. Please know that this this beer smelled great while in the primary.

I suspect I'll need to dump this batch. Any ideas as what went wrong? Very discouraging.

Bottle it and let it condition for a month or 2. then try it. There is a really long thread that Revvy posted that is a good lesson in something like this.

If it is vinegary than you have an acetobacter contamination, and you exposed the beer to too much O2.

or it could be a lacto infection.

I'm thinking acetobacter contamination, since it has that tell-tale 'sour apple' smell. The sediment on the bottom looks strange--too coagulated, although that may be because of the gelatin. I should have left it in the primary where it was cozy and untouched.

Just a thought: could I just be smelling a combination of beer and concentrated CO2 through the top of the carboy?

CO2 is nasty so yes, that could be what you are smelling.
If it were mine, I would wait and bottle/keg as planned.
How long was your appropriate time in the primary?

I may revoke the adjective "appropriate." It was two weeks. I don't think taking it off the yeast after 2 weeks did any harm, but my gut told me to leave it alone. My only reason for racking was that I had success in clarifying my previous batch in the carboy. I simply wanted to try it again, especially since the grain steeping made the wort a bit cloudier.

There's nothing wrong with your procedure, however, I normally leave mine in the primary for about 4 weeks. You might want to wait a little longer the next time but it doesn't sound like you've made a fatal mistake to me.

Thanks. As a newbie, I panic easily about these things. Appreciate the help.

RESOLVED! (I think).

I actually sampled the beer. There is a lot going on in this brew, which I suspect is a good sign: the flavors are not being overpowered by a vinegary taste. It's a little sharp and yeasty, but I attribute this to it being young. And as I suspected (see #6), the smell is (I'm almost sure of it) the result of sticking my nose in an area of concentrated CO2.

Also, it has been suggested to me that these young ales can often have a green apple presence that dissipate with time. If this sheds light on the matter, I've used Wyeast strain 1728.

I'll bottled this weekend and leave it alone for at least a month. I encourage my fellow newbies to read the threads on allegedly ruined beer. Chances are, it isn't.