Fluid buildup in lungs , chest and stomach

My mom is a diabetic, she went into respitory failure because of fluid buildup in her right lung. She was placed on a respirator, and a lung tap was performed, which removed a liter of fluid. The fluid was tested and came back negative. A chest tube was inserted and they were able to drain 3 more liters. They gave her an echocardiogram which was fine.her blood was acetic so she was given biocarb.blood tests were good after that.she is seriously anemic she was given like 10 units of blood over 3 weeks time..she had numerous ct scans and chest x rays, fluid built up again so they had to put another chest tube in, they extracted 4 more liters of fluid.they said there is no blood in her stool or in her urine.. they have no idea were the blood is going or where the fluid is coming from.. all the cancer tests came back negative.. she is on a fluid restriction but the doctors are scratching their heads because all the tests are negative, oh ya she was on the respirator for only 6 days cause her blood pressure was so low they had to stabilize it first.does anyone have any ideas please help she is swelling up again.congestive heart failure was ruled out, no tumors were found, renal function is o.k. she is on 4 liters of oxegen now hh level is 30 please help .... anyone got any ideas