swollen instep and very painful

I think you need to go back to your Doctor and ask for a blood test to check your kidney function. It maybe that you are retaining fluid which collects at the legs and that causes you to feel pain.
If you wear socks does the elastic leave a deep mark on your shin. I am no doctor but who knows. A course of diuretics may help your condition. Wish you all the best.

 

Lymphoedema is usually worse at the end of the day, and is improved quite quickly by elevating the feet.
If the Feet are stuck in tight shoes all day, they can certainly cause lots of different pains.

I would agree that you go and see a doctor, we won't be able to diagnose you over the internet, as there is too many thing we could miss.