Update: I have managed to reduce the sweaty socks/sewer smell by using a few drops of oregano oil in my shoes and castor oil on my feet each day - both of these substances are powerful antibacterials.
However, the downside is that they have their own strong, unpleasant smell as many other essential oils do and it can be noticed through my shoes as well.
Does anyone know any powerful odor absorbant that I could wear in my shoes?
It seems like these oils provide me with the best results so far so I would have to continue with them, even if they are still far from perfect.