hello, im 20 year old man and this past fews days i have developed a pain situated at my lower back. just above the rectum, it appears i have some kind of small ball under the skin, and im affraid it might be linked with my spine, so i avoid any possibility of medling even though it might be a really big concentration of puss or fat. It hurts when im getting up, when im going to sit, and when i sit i either have to sit perfectly straight or on pillows in order to restrain the pain as much as possible..i have no obvious difficulty in walking. an answer or advice would be greatly appreciated