What Causes Backache And Abdominal Pain After Taking Primolut Tablets?

hallo doctor iwas taking tab primolute n 5 mg last 21 days then i stoped came periods now four days but i feel severe lowbackache and lower abd pain ucan give me any treatment reduce pain before took tablet ido usg that shows endometrial thickening but before ihave hystery of pcod and small fibroid but now usg not shows