What does your oncologist say about it? Does it seems to radiate down your leg from the hip, and if so in the front or the back? Did you have any kind of precipitating event? Does it feel at all electric, or is it a dull bone ache? Is it positional? Is there swelling? It could be many things, including neuropathy, a clot, a pinched nerve, you name it. If you haven't consulted the doctor about it yet, I think you should, and make sure it is taken seriously. No point in being a hero.
I had pain that I would call almost electric--radiating down the front--from a nerve problem, years before CRC. I had wrenched my piriformis muscle, which was putting pressure on an adjacent nerve. Assiduous targeted stretches and so forth did no good. Couldn't sleep without hydrocodone or the like. What finally fixed it was accupuncture, which I think is really great for nerve-related issues.