I have a different weak point: my right knee. 

I work regularly to strenght it doing squats on a bosu ball and standing on the bosu ball on one leg while raising a dumbbell.

I'm pretty sure those exercises would also help strenghten the ankle. 

And shoes are key. I recently tried a new Broosk model and after a week I had to go back to the store and buy a pair of my regular model (Brooks Glycerin). 

 Have you tried running in barefoot shoes, like vibrams? 

 Have you done the running machine at the sports store where they measure your pronation as you run ? Quite useful to get correct shoes and insoles if you run often 

 Good point 

 It helped me alot. I used to run marathons and run long distances 

 Also I’ve pretty gnarly feet having broken my big toe and done a lot of sport. I went to see a foot person and they mapped my feet as i walked. They made specific insoles for my shoes. It made a big difference to pain i’d been having. Big relief 

 Cost about £300 but well worth it for me. They lasted for several years 

 Have you met my wife the podiatrist @mbhardcastle