Aiyo mama, that drop is concerning especially when you're already on obimin, definitely feedback this to your doc ASAP because sometimes the iron supplement itself tak agree with some mums, or there might be something else causing the drop yang kena investigate. A few of us in the mum group had similar experiences where the supplement didn't help, and our doctors either changed the brand, adjusted the dose, or found out ada other issues like heavy periods or absorption problems, so jangan tahan-tahan, mention this at your next visit or call the clinic earlier if possible lah. Hb falling like that while on treatment memang perlu attention.