When they discolour like you say do your feet swell up as well if so you may need to take water tablets as I am not a doctor and if the problem persists you may be ought to see your GP

Poor circulation would cause that. Get it checked.

I think If you had pain it would be neuropathy. If not poor circultion. Does it go away when your feet are elevated? Last month I had swelling in my feet. Then my feet mainly my left foot went competely numb. I saw dr and he wants to rule out a pinched nerve in my spine. Always go to your Dr when in doudt

Poor Blood Circulation suggest you see your GP But there again I am not a doctor

also could be neurophy pain I have it in the back of my legs and feet .its very painful .I cant do any shopping anymore .my daughter does it for me will hurt the back of legs and feet .I almost fall down .