I am making my second batch of Riesling from a kit. First batch went great. I am on my last racking and topped off this one with a bottle from my last batch. I haven't looked at it for several days. Today there is definitely something icky growing in there. Honestly, it kind of looks like brown brains and is at the top in the neck. There isn't any of the usual sediment on the bottom. I am assuming this one is a lost cause but any idea of what I did wrong so I don't make this mistake again?