Post a picture if you can. Fermentations all look different. What most think “may” be an infection, is usually normal. Infections usually take some time to show themselves too. I’d be surprised if you saw an infection starting after only 12 days. And even if it is an infection, there is no way it’s imparted any flavors this quickly. Infections, whether intentional or accidental, take months to begin imparting flavors.
There is a fantastic thread on Home Brew Talk where people post their infections. Once you see a few, you’ll know whether you have one or not. They’re pretty unmistakeable.
