you are on the hot spot

It's called a hot spot. Dogs get them. The deal is, they itch, and so they scratch. And they scratch and scratch and scratch. And then they scratch some more. And soon, even though the tick or flea or whatever the original source of the itch was is gone, that spot still itches. Infact, it itches more. It itches of it's own accord and it burns and even though there is no cause there is a very real symptom. The hot spot.
A friend of mine went to the doctor because she had exzema and or some other common dermatological malady and she noted this spot on her back that itched, especially, concerned really that it was something more and he explained to her that her itching had caused a rash. She itched because she scratched. And now, well, now she itched worse than ever. It's not called a hot spot when you are talking about humans, but still. It's called atopic dermatitis and now you need cortizone.
Vicious cycle, that hot spot.
And I think about this. Extrapolate. Metaphorically inspired, I ponder: how often do we create our own emotional and physical hotspots? Old ills that create new pains, ghosts of a past iritation now so potent they overshadow the original disease? And how do you know a hot spot from a cancerous mole from another typical outbreak? How do you know if it's time for the cortizone or a ritual delousing or if it's time to just cut the damn limb off?