I am 37 weeks pregnant and had sudden pain in my left foot where it hurts to even stand on it or put any pressure on it. I have almost fallen a couple times today because it will feel a little better and I begin to walk on it, then total loss of strength in the foot and if I putting pressure on that foot at the time, I almost fall. Also some numbing of the foot, both of my feet are swollen bigger than normal today, and the left feels tighter than the right. I have not injured my foot today or twisted it. I am 31 years old, 5'5, and 209 lbs right now at 9+ months pregnant. What can be causing this?