I just wanted to chime in on this... I had the Paragard IUD but I also had the numbness and tingling and the pain in my feet (doctors also told me it was plantar fasciitis). But I knew it wasn't plantar fasciitis because I would also get it in my fingers when things became really severe. I had pain in my calves... my pain feels like a burning sensation. There were times by leg/feet pain was so severe that I crawled on the floor to avoid standing.
The main reason I wanted to respond is because I also went to my doctor and told her what I was experiencing and she dismissed me. When I said... "well I've read a bunch of women online are experiencing similar symptoms" she gave me the same "well you can find anything on the internet" speech.
There is something that the paragard and the mirena both do to the body that makes us react this way.