Excessive bleeding periods every 3 month

Hi doctor my mother has thyroid & gets her periods every 2 months but the problem is after every periods she gets her hemoglobin % goes down recently we have admitted her & infused 2 bottles of blood but the problem continued she got periods again 3 months later & she complains of severe head ache & total body weakness after that. We had done ultra sound on our near by gynic advice & found that there is no problem hidden in stomach. Doctors have suggested to remove baby Pocket but since she already has thyroid we are scared of the side effects. This has become daily routine but it is getting worse day by day. Pls suggest is appropriate medicine to get this sorted. Currently she is using Orofer XT & Dexorange tablets for time being.