purple circular spot under the skin on my foot-Im a little scared its grown.

I've had this circular purple colored spot on the bottom of my foot for about two years. Its under the skin so I cant feel it and it looks like a broken blood vessel, but its circular and I've never had anything like this. Just recently it seems to have gotten larger and there is another tiny one in a different spot that has recently appeared.
Any ideas on what this is? Should I be worried? Should I seek a doctor to biopsy it? Im a little scared that it could be cancer.

thanks everyone. Tweet