Unknown cause of health issues

I thought I would post my question here to see if anyone has come across a similar situation or could shed some light on our situation. My aunt is currently in the hospital. The doctors are unable to diagnose her health issue. They initially thought it was an autoimmune disorder or infection of some type but after trying steriods and anti-biotics that have been ineffective, they are unsure. It initially started out as a swelling of the soles of her feet. It then spread to her knees. She found it extremely hard and painful to walk. She also noticed that her fingers would go numb then after a while would hurt and turn purple as the circulation returned to her hands. This went on for a few weeks. She then developed a fever and had pain all over her body. She screamed in pain if anyone touched her skin. She was taken to the hospital where she was admitted. She has since developed fluid buildup on her lungs and in her stomach as well as the fluid on her knees. She also has a rash that first appeared on her back and then moved to her stomach. It is now spreading to the rest of her body. The tests show low red blood cell levels. The fever is constant and goes up and down throughout the day. She has a constant pain that she describes as "in her bones". They also said she is anemic and has low folic acid. She is constantly thirsty also although I suspect this may be due to the fever. They have stated also that they have ruled out rheumatoid arthritis. Any help anyone could give would be greatly appreciated as we try to figure out what is the culprit here. Thanks in advance for any advice you can give.