Does this sound like skin mets?

[Jane]

I'm wondering if anyone has had a similar experience - and what was the outcome:

I woke up a week ago with a small (dime-sized) fluid-filled blister on my right shin. It came out of nowhere - no injuries, bumps, etc. I lanced it and went about my day.
The next day, it scaled over but looked very strange. Each day since, it's gotten worse and worse. It's black, brown and spotted inside - no scab, just an odd crust. It's red around it and is very painful to touch. It's irregularly shaped but hasn't gotten bigger.
I've seen 3 docs - gotten antibiotics - and had it biopsied and cultured yesterday by a dermatolgist. I won't get results until after Christmas.
It seems to have classic skin cancer characteristics - could it be mets and is it common that BC spreads to skin like that?
I'm very scared. Any comments appreciated.
Jane

49-year-old mother of two wonderful kids, 10 and 12
Diagnosed in Feb. 2005, Right breast Stage 3a, HER2 3+, ER+, PR+, 6/15 nodes postivie
Bilateral mastectomy
All the usual chemo/rads/one year of Herceptin
Now on Arimadex