Thanks for the additional information.
As per your description,the size of ovarian mass is not so big to rule out ovarian cancer by itself..
Chances of ovarian cyst are more likely which are usually benign.
Pain in lower back,heavy,painful periods can be associated with Endometriosis.
However you need to undergo serial ultrasound and further blood work like CA 125(one of ovarian tumor markers) to screen the size and growth of ovarian mass in next few months.
If the mass gets bigger in size over the time then malignancy should be rule out.
In most of the cases,ovarian cyst resolve by their own in few menstrual cycles.
As you have severe pain so it's good to see your gynecologist for proper management.
Hope this helps.
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