I'm not sure but some viral infections cause that. I had shingles before but through the outside, they hurt really really bad and they were very itchy. First I developed a rash, then little red round shape blisters would develope and pretty soon my back, legs, and chest was filled with the shingles. My doctor admitted me to the hospital gave me Acyclovir I.V., creams EMLA (lidocaine, benzocaine) and morphine & neurontin for the pain, and Atarax and Ativan for the itching, sedation, and nausea. At the time I was 1 year post bone marrow transplant, I had leukemia. Also at the time my white blood cell count was 0.5-1.0 which is low the normal WBC is (4.0-12.0). Well I think the ball that you develope could be the shingles and you should go to the ER or something soon especially if it hurts a lot or if you have any fever, nausea, unusual breathing, etc. take care and good luck, hope this helps, you should visit websites on this like:
http://www.medicinenet.com/shingles/article.htm
http://www.ninds.nih.gov/disorders/shingles/shingles.htm
good luck
One other thing I was thinking about is Postherpetic Neuralgia which developes after the shingles infection and causes pain. You should tell that to your doctor I would recommend neurontin or Lyrica for the pain. Maybe you should see a pain specialist? well good luck
I have had pleurisy several times, it is very painful, they say that when you get it, it always comes back, the only thing that I took was 800mg motrin, it hurts to breathe, and sometimes, when I had it under my left arm, I couldn't raise of arm because of pain.