One of the mechanisms the body uses, as in the formation of abscesses, is that when waste material has been packed away under the skin they are meant to fester (or become infected) so that this process will be able to break through the skin and allow the discharge. Greasy Heel is like this and treating it with anti-biotics, antiseptics and the like really don't address the real problem although they often appear as in your case to temporarily relieve the discomfort.
I find the best treatment is to use stimulants to the circulation within the hoof along with healing and anti-inflammatory herbs internally. I have formulated my Hoof Oil with all this in mind and mostly there is nothing more needed than regular rubbing with this Oil which continues long after all signs of the problem have gone. We are aiming to improve and maintain a slightly improved circulation within the hoof and allow the whole structure to maintain itself in better health.