Could it be a hotspot? Moses had one a few years ago that went from the size of a dime to the entire side of his face over night. Do a search on here for Moses hotspot and you can see pics and treatment recommendations.
Vertericyn is handy to keep on hand.
Something else to consider:
Pythiosis of the skin (or cutaneous pythiosis) results in the development of swollen, non-healing wounds, and invasive masses of ulcerated pus-filled nodules and draining tracts. Tissue death (necrosis) follows, with the affected skin eventually turning black and wasting.
This infection is caused by direct contact with water that accommodates Pythium insidiosum, a water borne fungal parasite. It is usually swallowed or inhaled by the dog, and from there makes its way to the animal's intestinal tract.
Last edited by GSDAlphaMom; 05-13-2014 at 06:28 PM.