welcome to hcm,
I really appreciate your concern,
THe problem here is called
endometriosis.
During a normal period ( menstrual cycle ) , blood flows out of the uterus through the vagina.
In this disease, the menstrual blood travels in opposite direction and enters the pelvis, leading to deposits of endometrial tissue in the pelvis.
The cyst in your ovary is due to endometriosis and called as chocolate cysts.
This explains the pain during your period, that you are having.
Endometriosis also leads to Adhesions.
The treatment mainly consists of
hormonal treatment for 3 months -
oral contraceptive pills,
progesterone pills,
Danazol etc.
If this fails, then surgical removal is the next step for this condition which i hope you will be undergoing.
Please feel free to ask if you have any further questions,
Thanks. Regards.