?Endometriosis Flare

I was admitted to hospital on Sunday with pelvic and was discharged last night on morphine. I'm waiting for outpatient surgery though the doctors think I have endometriosis and am having a flare up. Has anyone else got this abc experienced flares? This one has been going on for 11 days so far with no end in sight. I'm taking loads of painkillers as well as morphine every 2 hours!!!! I would just like some indication of how long this is expected to last