It seems as though you are having problem with the way you place your feet while walking. You will need to get your feet and footwear checked by a physiotherapist. Depending on how the footwear are getting worn out, a physiotherapist can advice you how to correct the way you are walking.
Next Steps
Please approach a physiotherapist nearby or post pics of your feet in normal standing in all four directions viewable. And also wearing the footwear you are using most of the time. I might be able to advice certain corrections based on that.