Our cat has a whitish, tag like growth on the back of its neck with what looks like a lump or wound at its base. At first I thought it was a tick but it doesn't look like one. It looks like a big pimple, about 8mm long and 2mm across. Can anyone suggest what it might be? He's had it for over a week now and it has remained the same size, if it were a tick would it have dropped off by now? It doesn't seem to bother him unduly.