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Definitely agree with others that this is not Hummingbird. It's possible that you were hit with something more like Penguin - Google only warns about manual penalties in GWT, not algorithmic penalties. Also agree with others that these tactics are absolutely likely to get you in trouble sooner or later. Unfortunately, new sites are very vulnerable. I believe there's almost a reverse sandbox in play right now (for lack of a better phrase) - new sites get a grace period and can rank pretty well out the gate. Then, Google starts looking for signals to sort out if the site has long-term potential and should continue to rank. If you've hit low-quality tactics hard very early, this is when the hammer is likely to come down, and it's going to come down hard, because you don't have many positive signals in play. Without a foundation of solid, legitimate links, social signals, etc., and spammy links are going to do a lot more damage. If you've hit these tactics really hard, and the sites are that new, I'll be brutally honest - you're probably either going to have to cut or disavow the vast majority of your links or just start over. You pushed too hard, too fast, from your description.