i have a dull back pain coming and going for 3,5 weeks now.. sometimes beneath the ribs in a hole area, sometimes in the right flank area like a pinch and sometimes the same on the left. i also had some change in the frequency of urination (increased), and feeling difficulty to pass all the urine and sometimes the back pain was going away after urination. I am 27 years old male, a bit overweight, and just went out from a very stressfull period. What can it be?