Relapse?

I just finished 2 years of "Maintenance Rituxan" back in March, and up til then it had gone very well.  My hemoglobin levels had returned to normal - I wasn't anemic anymore.  My IgM levels had dropped down to around 1300 (the high was somewhere around 3000 when I was first diagnosed), which is well above normal, but is much improved and not very dangerous.  But then early this month, I went for my 3 month checkup and my hemoglobin level has dropped back down into the "anemic" range.  Now this could have several causes: the disease may have come roaring back, although it's unusual for it to roar like that.  It's generally an indolent, or slow-moving, disease.  I could be losing blood somewhere, although there's no obvious evidence of that.  Or there could be something going on, perhaps related to the disease, that's killing red blood cells.  Or it's possible that something is preventing my system from absorbing and processing iron, the "key ingredient" to hemoglobin.  So I went back up to Boston on Monday to see Dr. Treon.  He did a bone marrow biopsy, to gauge the level of the disease, and also took several vials of blood to test for other eventualities.  I should get some answers - or at least some next steps - late this week.