What Causes Pain In Sides And Lower Back After Having Medical Abortion?

i had a medical abortion over 3 weeks ago, and i went in for my check up 5 days after...the nurse gave me an ultrasound and said everything was complete and looked good....so every since iv been having pain in my sides and lower back...light stabbing crampy feeling. thinkink back i had lots of pain the day i missed my period for a week...that pain is how i found out i was preg. i had an eptopic two years ago and have endometriosis....and they also seen a cyst while doing the ultrasound.. my question is what could this pain be from, its kinda uncomfortable but not enough to disrupt my life...going to the bathroom is kinda painful tho?!?