Sorry you are having all that pain. About five months ago, I went to the e.R. With the same symptoms. They also thought I had kidney stones... Did not !! They sent me home with little explanation, and gave me pain pills.
They completely dismissed my back pain, after the test showed negitive on the kidney stones, and said that I was having some gyn problems to see a gyno.
So, I did, turned out that I have endometriosis. It can cause severe pain, irregular bleeding, pain down one or both legs, and several other symptoms. There are questionairs on the internet to take to your doctor, if you feel that you have those symptoms.
I really hope that you don't have that, but see a doctor for sure.
Hope you are feeling better soon!