Hi, thanks for asking in Healthcare Magic.
You are having Brachial neuralgia
ie., pain radiating down the arm. It is common among middle aged persons. The pain usually starts as a pain in the neck or shoulder and spreads down the arm. The shooting pain to the tips of the fingers is due to the irritation of the nerve roots.
But first you have to rule out Diabetes. Your high cholesterol
, improper wound healing
(un controlled spread of rash) and increased body weight are suggestive of Diabetes.
or Periarthritis due to Diabetes can result in severe shoulder pain
It could also be due to " Cervical rib" or "Cervical spondylosis".
Radiological investigation like X-Ray spine will help in diagnosis
Clindamycin and steroid creams will help in controlling the rash.
I hope this answer is helpful.