Why do people call African Americans racists?

Ever since President Barack Obama said that that Cambridge Police officer acted "stupidly", its been a free for all calling African Americans racists for simply stating how they feel oppressed here in the USA and are tired of it. Ironically, African Americans are the ones who fought and died to end racist activities of Whites and their laws of segregation, lynchings,slavery, senseless beatings and s, burining of African American and other minority businesses and racism throughout American history. Whites were the ones who came up with these concepts and tried hard to enforce them. You will still find Americans flying Confederate flags that represent the Old South led by the Grand Old Party. These and many other practices such as the suttle Jim Crow laws that are practiced each day is racist, but not on behalf of African Americans, so when did we become the racists?