What does my hematologist/oncologist mean by this?

Hmmm...it's hard to tell what he means by that. I think it means he can't figure it out, and will let the blood work decide. Doctors do this all the time. :) You do have a wide variety of symptoms that may or may not be all connected. I am sure they will find out soon. So sorry you are suffering..Good luck to you with the test results. That low grade fever bothers me...I get that, too! But I have a condition called Hidradenitis supperativa, (Open wounds in my groin/labia/tailbone) It could be an infection somewhere in your body that is causing the low grade fever, and thus giving you all the symptoms you mentioned above. Anyways, I'm babbling. Hope you feel better and it's nothing serious.