Bruise on my back where my kidney would be. what would cause this. i haven't hurt myself or been hit by anything?

See professionals...: Bruise there is probably not related with kidney itself. Instead, watch for possible low platelet count. This is just a guess for your age and described condition. But it's most advisable to consult with an expert, but at least with you pcp. Meanwhile, collect any potential related symptoms such as general weakness, fever, or history of upper respiratory infection ... Before going to see...