I have had a greenish hard scab on my scalp for the past few months. Within the last week it became swollen under and around and was painful when touched. Today I squeezed the area surrounding the scab and the scab itself squeezed out followed by a good amount of yellow smelly pus. The scab was hard yellow and thick after it came out. The surrounding area is still slightly swollen and there is a hole where it once was. I squeezed until the pus stopped and before I saw any blood. Is this a sign of some particular disease? Should I be concerned? My health history is normal however I have not been able to afford to see a physician for this issue. 28 yrs old. Smoker. Drug free.