What Causes Itchy Painful Blue Marks On The Leg?

I had a blue mark on my leg for 11 years, the mark looked like a popped blood vessle, over the years doctors just wrote it off as such. recently it started growing over a two week period it double its size and protruded from my skin. it was painful. i accidently scratched it or rubbed it this morning and something came out of it! its a jagged semi hollow brownish with some white seed like or rock like substance with a small amount of pus. all the discoloration in my leg is gone! I was wondering what this could be. it does not smell or look like the contents of a cyst or pimple of any kind... also i noticed there is another blue mark on my back and a larger bump on my head under my hair. is this something to be conserned about. i can find no pictures online that resemble this.