Hi, I had a smiliar experience when I had a cyst rupture. Not to say that is what yours was, but def push for an ultrasound to see what is going on in there. They did an ultrasound on me and were able to find lots of fluid from the rupture. They watched it for a few months & it finally reabsorbed.
I was unconscious by the time my parents took me to the ER (I was living in a dorm room & a sorority sister called them to say I was unconscious). I had been having lower back pain & swelling for a few weeks beforehand but I just ignored it. I was in pain for hours before I was taken to the hospital! I feel your pain! So sorry!
Good luck and be sure they check you out really well.
Hugs
