I Have Sever Pain In My Left Foot . This

I have sever pain in my left foot . This started about 3 weeks ago and started mainly in the heel area. It has steadily progressed to the arch and top of my foot. It is painful to walk and shoes with some kind of padding in them do help but not for long. Putting weight on the foot is excruciating and some times nauseating. After sitting for awhile, I get up and it takes a few seconds and up to a minute before I can put any weight on the foot. It worsens as the day progresses and I have almost fallen when I have to get up in the middle of the night to go to the bathroom