Hi M2412
The prednisolone is likely the cause of the bleeding. It's a known side effect of corticosteroids, but should be mentioned at your next appointment.
"After administration of corticosteroids in a postmenopausal woman an episode of menstruation like bleeding can be expected. This is probably due to a transient drop of androstenedione. In premenopausal women a transient change in menstruation cycle can be observed.
However, since postmenopausal blood loss is also an early sign of gynecologic malignancy, we believe all women with this complaint should be referred to or visit a gynecologist."