Tie your shoes really tight? I find that can cause friction like rubs.... from the foot being mashed into the shoe footbed?
I do tie them pretty tight since I have narrow feet. Maybe I’ll try it a bit more loose next time!
Why didn’t I think of this
Em, my feet are narrow too, I found that I had to tie the top tight but the bottom loose. ie try to keep the heel in place but let the pressure off the rest of the foot. I don't know if that would work for you.
Have you tried some of those origami lacing techniques?