This research study is being done because we have not yet been able to find the best treatment for recurrent or advanced head and neck cancer (SCCHN). Pemetrexed and gemcitabine have helped fight against SCCHN when each was given by itself. This study is different from others because it tests these two drugs together, which has not been tried before in patients with SCCHN. We will see how well these drugs can work to help to control or shrink your cancer.