If Venous , you would have obvious swelling, possible risk of clots, heaviness, color changes..so I'm thinking either nerve, or myofascial based (restrictions/impingements which can be worked with and usually improved)

Try some of the gentle passive postures I posted, if those are too much and increase pain. then only do a yoga "corpse pose " with diaphragmatic breathing & visualize relaxation of muscles . best to do those many times a day.
It may not be a fast fix , but over time you should feel improvements. you may not even notice at first..