Red round spots on shins and foot

Hi all,

For a few years now I've been breaking out in red spots around the shin area
and top of the foot.  They are very deep red, pefectly round and do itch when they
first appear.  They actually look like a mosquito bite when the bite is starting to fade away.
As for size, I'd say about the size of the top of a pencil eraser.  They feel slightly raised
and will eventually go away, but it sometimes takes weeks for them to disappear.  When
I press in on them, they do not blanch in color.  

If anyone might be able to help me, I'd sure appreciate it...thanks!