Doctor told me my arch in my left foot is collapsing, my ankle also hurts. she only offered inserts as a solution. what should i do? i run a lot.

Run, Run Runaway.: Well, it certainly is a starting point. But more than likely, you probably already knew that. Without knowing exactly what information she based that treatment on, it is difficult to day if anything more could or even should be done at this point. My suggestion is, to remove all doubt, seek a second opinion. Perhaps with a specialist that has experience dealing with runners.