Ankle pain

I was doing my run on my treadmill yesterday. I was scheduled for 14 miles. I started getting occasional shooting pains in my left ankle around mile 7 or 8. They would only last for a step or three, then go away for a bit. It felt almost like my ankle might give out and dump me on my face. I took a short break, then continued running. The pain kept coming back. But 14 miles is 14 miles! I will be running longer than that in a month. So I kept going. Towards the 11-12 mile mark, the pains were coming more often. At about the 12 mile mark, I started walking. I walked the remaining couple miles. I am not sure what the deal is. I will keep an eye on it, and hopfully it is just an anomally.