An abnormal head is one of the most telling ways to identify an infection, but I wouldn't worry quite yet - first of all, most infections taste just fine, and I've even had a couple of bottle infections that ended up my favorite in the entire batch!
And you may not have an infection after all. How old is the beer? It may just be green and have a lot of yeast left in solution, which can affect the head and the aroma of the beer.
The Fiesty(sic) Goat Brewery est. 2007 & Clusterfuggle Experimental Ales est. 2009
Primary: Saison, Berliner Weisse, sLambic I, sLambic II, IPA, 70/-
Secondary: Orange Blossom Mead, Flanders Red I
Kegged: Fat Man Porter w/ 1469, Fat Man Porter w/ 005, Centennial Falcon w/ Conan, Centennial Falcon w/ Denny's, Barrel-aged Fat Man Porter, Belgian Dark Strong, Dark Mild