Hi,
Causes, when we speak of lower back pain could be several, such as: urinary infections,
urinary tract lithiasis, acute lumbago, column pathologies, inflammatory colonopathies among others.
When you mention
pelvic pain joined to lower back pain, I begin to rule out some diagnosis and stay with: urinary tract lithiasis, urinary infections, inflammatory colonopathies.
And then, when you mention the
flatulence (a lot of gas), although you deny disorders of the evacuation pattern, I stay with a starting diagnosis of inflammatory colonopathy. This as you may not know, is a syndrome, because in turn it can have multiple causes. So, with your age, yes it is recommendable a
colonoscopy.
Also if I were your doctor, I would suggest a stool test,
urinalysis and a renal echogram to get a clear diagnosis.
Hope I have answered your query. Let me know if I can assist you further.