The Joker is playing the amnesia card. Accused mass murderer James Holmes told jailhouse workers that he remains stumped about what landed him in a Colorado lockup, a jail staffer told the Daily News. “He claims he doesn’t know why he’s in jail,” the worker said Thursday. “He asked, ‘Why am I here?’” Holmes, 24, who is charged with shooting a dozen people to death and wounding 58 more at a screening of the new Batman movie, was also complaining of a stomach ache caused by lousy jail food after his sixth day at the Arapahoe County Detention Center, the...