Complex sentence: The Gigantour took place from 26 January to 28 February 2012, but Motörhead missed the final four shows because Lemmy had a combination of an upper respiratory viral infection and voice strain, resulting in severe laryngitis.
Split into simpler sentences: The Gigantour took place from 26 January to 28 February 2012. Motörhead didn't play the final four shows during this tour, since Lemmy has experienced a combination of a viral upper respiratory infection and a voice strain, resulting in severe laryngitis.