My cat hurt her paw. this starts with a white sore on paw with a black dot, swells, then becomes very infected, then drains a thick white pus and rapiedly eats the skin. at first we thought of a insect bite, but these are inside cats and this is the third cat within a matter of days. Any help at all would really help us to prevent this. I have never seen anything like this and the vet can't figure this out. Please help.