I recently brewed a Berliner Weisse using a three day sour mash at 110-120*F followed by a 30 minute boil. The OG was 1.031, and it's been fermenting for 2.5 weeks. Within the past 3 days it has reached its FG of 1.004. The issue I'm faced with is the unpleasant aroma of butanoic acid (vomit)...