Hemoglobin dropped 9.8 to 8.9 in less than 2 mos. iron, b12 ok, no hep, no hiv. now being checked for lupus-already have psoriasis. if that's negative then do bone marrow biopsy. is this really bad?

May be: The fall is not great but the levels are low especially if your iron level is truly normal and there are no other obvious reasons for the low count. A bone marrow study is not pleasant but can give you and your doctor valuable information. Seeing a hematologist (blood specialist) may also be wise.

Blood loss/dilution: Hopefully your doctor retested, to rule out lab error. Assuming the result is real, you are either losing blood or diluting it with fluid. Women tend to gain & lose lots of fluid, and it may be as simple as that. If stools are black or bloody they should be looking for bleeding in intestine. Psoriasis will not cause it. Only way to know is to do the tests. Let us know result!

Check for bleeding: Occult blood loss can also cause HGB to drop as can unfortunately, some types of cancers. I don't mean to scare you but have you had an abdominal ultrasound, checked for hidden blood in stool, etc. If not, you should. Are you also fatigued or have any abnormalities? Ask doctor to be very diligent in your work up. Have you had an serum protein electrophoresis. You should have complete anemia check.