bursitis after full knee replacement

My knee was replaced in 2006 a zimmer implant.  I  am suffering now with bursitis found on cat scan.  I can't walk the knee is severely swollen hot and extremely tender to the touch.  I am with a pain management doctor taking percocet and naprosyn every day.  I have had pain and swelling ever since the surgery.  The pain is now crippling I can barely walk with a cane can't sleep at night drive a car without total misery.  knee is severely swollen and hot to the touch.I cannot do anything! My knee feels like it will collapse underneathme and pain is so severe I scream out.  My cat scan showed bursitis.  My doctor wants to give me a cortisone shot another suggests draining fluid.  I can't even stand the touch of a feather I feel the bursae sac might be infected because i have the chills am always cold.  Can anyone offer sensible advice as to where to go for treatment and what kind.  I feel I need to have a biopsy of the fluid drained for infection as well as a steroid injection. I'm afraid if the sac is infected it will go to my heart.  I had a septic implant in my mouth removed and15 years of hell two sinus surgeries staff infections.