Welcome to HealthcareMagic forum.
I have heard of lower abdominal pain
following strenuous physical exercise, but on mild exercise such as walk is something new.
Anyways, the pain could be related to muscle sprain or a hernia
(if the pain is located at the same spot). Since a colonoscopy
was normal, it is unlikely to be related to an intestinal condition.
pain does not present as pain over the right lower abdomen.
You can consider an ultrasound
abdomen localised to the area of pain. A competent surgeon should be able to guide you through the test.
Hope this answers your query.