What Does Sores In The Back Of Head Imply?

I KEEP GETTING SORES IN THE BACK OF MY HEAD AND IT IS TWO AND THREE AT A TIME. THEY START OFF SMALL AND GET VERY INFLAMED AND VERY SORE AND IT TAKES WEEKS FOR THEM TO GO AWAY AND WHEN THEY DO I GET MORE OF THEM. WHAT DO YOU THINK THEY ARE AND HOW CAN I TREAT THEM TO MAKE THEM GO AWAY?