I've been chronically anemic for years. Don't know officially why I'm anemic (and the doctors I've seen all seem to blow it off as "anemia of chronic disease" and don't try to explain it further, or else just tell me to take iron pills, which I can't do), but I strongly suspect Lyme and/or Bartonella.
Antibiotics may also cause anemia as a side-effect, so you might want to ask your pharmacist if any of the meds you are taking can do that.
Good luck & take care,
Chronic Lyme Disease, Gluten & Sulfite Sensitivity, Many Food/Inhalant/Medication Allergies & Intolerances, Asthma, Gut issues (dysmotility, non-specific inflammation), UCTD ("Secondary Lupus-Like Syndrome"), Osteoporosis, Anemia, Lymphopenia, intermittant Pancytopenia, chronic malabsorption/malnutrition, etc.; G-J Tube; Currently TPN-dependent.
Meds: Zofran, Pulmicort, Vitamin B12 Shots, Heparin (to flush PICC line).