Be careful of bleach.. It can burn not to mention bleach the hair.. I suggest something with tea tree oil(melalucca), a produce called Calm Coat works well, or what I use most of the time on skin yuckies is Desitin, aka babybutt cream.
I havn't heard of it burning the horses skin, it kills all the fungal skin...it works wonders on greasy heel.
Acually, I have cut out his Millrun and im feeding him equalibrim, which seems to be working, the lumps are reducing. But are still present...