Collapsing Ankle/Foot

Any ideas?

Here's the scenario:

I've been increasing my running over the past couple of weeks, but not exponentially (9 miles/week total)

Over the past couple of days, my calves have been tight & I've been stretching a lot.

Today, while in a deep knee bend @ work (doing a task on the floor) my ankle collapsed.  Severe, exquisite pain in the inner arch spreading to the achilles area & around the foot.

I have full range of motion, but there is crackling.  No pain on range of motion.  There is some pain on weight bearing, but not too bad.

Twice since then, when I've been walking, my ankle/foot has collapsed in the same manner - same pain.  SEVERE!

Obviously, I'm doing the RICE thing as much as possible (I'm still @ work - nurse 12-hour shift).  And I'm going to try to get in w/the podiatrist tomorrow.

Anyone else ever experience anything like this?

Kim