What Causes Severe Pain In Heel?

I am having really bad pain in the back of my heel. I already was checked months ago and was diagnosed with planter ficiaotus. I ordered and received shoe insoles specially made for my feet. That was months ago. Just last week all of a sudden I couldn't walk on my left foot. The excruciating pain was coming from the back of my heel. Since I have been resting it after work and icing it. Its helping "a little" but not going away. What can and should I ro?