I agree with everyone that you used way too much dark malt. 1 lb chocolate malt and 4 oz black malt would be plenty of dark malt. Black malt is very intense and 1 lb of it on top of 2 lbs of chocolate malt would make for a very acidic mash, as Denny said. Also, consider that fermentation temperature will almost always be 4-8 degrees warmer than ambient temperature. In my experience, 4 degrees for lagers and 6 degrees for ales is pretty typical. Your fermometer wasn't lying to you.
My advice for next time: try out a recipe calculating site like brewtoad to help you at the planning stage. I also recommend using published recipes for inspiration. The AHA site has plenty of great recipes to check out.
My advice for this batch: give it a few more days or a week and see how it is. Don't try to doctor it; that has never been effective at managing off flavors, IME.
Too much dark malt is where my head is right now too. Not on the yeast at all as some suggested. My house fluctuates in temp because it’s starting to get cold. I do not think this fermentation was ever really too high in temp, at least, not for more than half of the fermentation.
I do use a beer calculator, BeerSmith, but never remember seeing anything about this batches ph. I also look for recipes on the aha and tweak them.
This beer has been in secondary for 4 full days now.
I think I might keg this weekend and see what happens.
Many people were talking about the turn around time on this beer, but, it will still get me drunk and if it’s undrinkable, a valuable lesson will be learned. I was not the most patient with this fermentation, but like I said, it took off like a rocket ship and has been sitting in the mid 60s since it stopped.