If you're going to try the Tricide Neo from what I understand you don't want to do any invasive procedure or surgery on the foot - it should help dry it up.
It looks like he may be developing infection - so techinically it could possibly be classified as Bumblefoot which is basically an infection caused by the staphylococcus bacteria which enters the chicken's system through a cut, scratch, injury or an irritated area on the foot.
Soaking in epsom...