What Causes Itching Sensation All Over Body And Bruises On Knees And Thighs?

Hi,I ve been itching all over for almost 2 weeks my body looks like a cats scratched it. I notice also i have bruising on my knees thighs and legs and back were I am itching. On monday my dr. gave me cortisone and litocane but it doesnt seem to help he gave me another dose today but still going nuts can t quiet function. What could this be?