Simple cysts (fluid filled inclusions) form on the ovary every month in women of reproductive age. They can grow up to 3-4 centimeters in size and not be a problem. They are a natural consequence of monthly egg development and ovulation. That is why they come and go. If they are under 4-5 centimeters, they should not be causing pain. Hemorraghic (a form of complex) cysts are nothing more than a simple cyst which ruptured to release an egg, then reclosed and filled with blood (also can happen often). Small amounts of free fluid in the cul-de sac is also normal.
If you are having pain requireing narcotics, a source needs to be found. a sub 3cm cyst does not explain it. Possible causes: pelvic infection, fibroids, musculoskeleta, bladder (stones)l.
Many women with pain after hysterectomy can have myofascial trigger points in the pelvic floor or abdomen and back which can refer pain into the pelvic.
Get evaluated by a gynecologist. If this workup is negative for any credible causes, then go see a pelvic floor physical therapist, to see if pelvic muscle issues may be at work.