Please see someone about this; it could be any number of things.

I was completely surprised one time by lower back pain, vomiting, diff breathing, and pain into my shoulder .. turned out to be kidney stones (some in the kidney & some lower down in the ureters causing the lower back pain) with a kidney infection and it was advanced. I had no idea before then.

However there are LOTS of other things that can cause similar symptoms. Please get checked ASAP!