@areichel
Your symptoms sound similar to mine. Was the fluid that was aspirated from your swollen knee bloody or otherwise? If it was bloody, were three test tubes sent to "a special lab on the east coast" to determine what was causing the bleeding? I have something called "Recurrent Hemarthrosis" of the knee. It is very rare. For most people it can be remedied by Genicular Arterial Embolization. That didn't work for me, but I am having exploratory surgery tomorrow morning and hope this revision surgeon can find the cause, then fix it. Keep searching for answers. I've been bleeding inside my knee socket for 4 years.