Regarding the sores on the back of your head, two conditions come to mind. One is when the bacteria that cause boils begins to live on a part of your skin, repeatedly causing boils in that area. That condition can usually be cured by proper antibiotics and, in addition, local scrubs. Another condition that comes to mind occurs when curly hair is cut short so that the hair as it grows turns into the skin, causing irritation. If your hair is not curly in this area and the sore are not occurring where hair is cut short, this is unlikely. Skin conditions require a trained eye and are not diagnosed at a distance. You should see a doctor, at best one specialized in skin conditions, for both of your problems.