What Causes Severe Pain And Frequent Urination?

I have been to five doctors in four years. I have had every test in the book. No one can find the reason why when I m laying down at night my left side begins to give me extreme pain. I end up peeing almost twenty times at night . When I finally do fall to sleep I wake up to pee. In the morning my stomach is really gassy and still have the extreme pain for about thirty minutes then it goes away until I lay down again at night. It the same process every night. I ve been tested for diabetes and I do t have that, ph bacteria don t have that, kidney stones, kidney infection, hepatitis and all sexual diseases came back don t have any of it. My prostate was normal and no cancer and right size.I do realize when the pain gets extreme too bad putting pressure on the side makes it the pain decrease a little. Every doctor I have seen told me they are stump and gave me flowmax and pain killers and they never worked. I was even giving inflammatory medicine and spasm medicine and nothing seem to work. I ve even taken gas x at night and still same pattern. Any advice could help and I m thirty years old and a male . Thanks