Ok, I'm going to go to my own doctor here shortly, but I want your
advice on how bad this sounds.  I'm a 24-year-old male, and I noticed a
suspicious mole on my upper buttocks about 2 years ago.  I have a good
many moles on my body, but nothing too out of the ordinary really, and
I have a cousin who at a young age was diagnosed with a sort of "pre
skin cancer."  Anyway, about the mole, it was weird because --and I kid
you not-- after I noticed it and went for the initial consultation to
my primary care provider, it, over the span of two weeks, TOALLY
disappeared, or at least turned from being brown to pink.  When I went
in to give the biopsy sample to my primary care provider, I had to show
him where it "used" to be, but it wasn't too difficult since it still
had a pinkness to it.  So, 2 bad signs were shown here:  a new mole
growth, and its disappearance within the span of about two weeks.
Anyway, there was no cancer/pre-cancer found from the biopsy, assuming
they did it correctly.  Now, two years later, in the very same spot
where the biopsy occurred, the SAME sort of mole has returned.

I guess my question is how often do these types of mole-changes happen
in people with no skin-cancer?  I should definitely have this biopsied
again, right?  If it wasn't cancerous the first time, does this mean
there's a good chance it's not also this time (even though I should
still make sure)?

Thanks...