22buddy

I have had kidney stones ten times and although it wasn't exactly the same every time there are a few keys factors that were similar.
The pain usually starts in the back area or flank and then travels around the front as the stone travels from the kidney to the bladder.
Once the stone leaves the kidney the pain in your back will go away. It might remain a LITTLE sore but it will seems like a miracle.
Also it isnt an ache but a SHARP knife like pain. ( atleast for me all ten times)

I have never heard of anyone being constipated or having heartburn with kidneys stones. However vomitting due to the pain is normal.
On the other hand your kidney is not just an open container like a balloon. It is a fleshy organ. meaning that inside the organ there are fleshy parts where a kidney stone can hide. Meaning you could have a stone that hides and bounces around once in awhile. This is what explains them growing in size. If not they would flush out before they grew to be so large they can't get out.
Have you had any ultrasounds of your kidneys. This would show if there is not only stones but a loss of bloodflow to them or enlargement of some kind.

Hope this helps and hope you are felling better soon.
Personally it sounds more like an intestinal problem to me which can also cause a lot of back problems or even a female problem,