Hi, I have a pain on my right side just above my hip in the fleshy part of my side which I would say is more towards the back rather than stomach.  It is not a constant pain it comes and goes.  It does not feel muscular.  I am of slim build exercise regularly and am 41 years old.
HelloActually this could be appendicitis, a kidney stone, or perhaps a muscle pull cant pinpoint the diagnosis without being able to examine you, so I suggest you see your doctor about it