Cancer patient with unknown blood loss

My brother has testicular choriocarcinoma cancer. 3 regimens of chemo, 2 surgeries, bone marrow transplant and head radiation.   Metastasis everywhere including the brain after 2 years.  Highly anemic needing blood transfusions every 2-3 days with fever.  No hemolysis, bone marrow still producing, no internal bleeding.   Doctors cannot find source of infection or the reason for continuous blood loss. Does anyone have any ideas why he keeps losing blood?

[luvkenken]

Sorry I post this to the wrong forum.  Don't know how to delete.