Ive had dull leg pain for years. its not in the joints, temporarily feels better with heat and movement &has been "migrating" recently. what is it? :/

Not sure: Very generic description. Where exactly is the leg pain? In the feet or further up? If it's in the feet and soles then a peripheral neuropathy can be considered especially if there is a history of diabetes, or other risk factors such a chemo treatment. Neuropathy tend to involve both legs so if the symptoms are unilateral then something else like a radiculopathy should be considered.