Thanks for the query.
Sometimes after ovulation the ruptured follicle will persist and form a cyst
Usually these will subside without the need of medication.
But some may need a hormonal
therapy. May be because of that your doctor given you progesterone
As now your regular menstrual cycle is got influenced by addition of progesterone, the bleeding you got is withdrawal bleeding.
It can be some what different from regular menstrual flow. So, no need to worry.