I read your query about Boil on Arm.
First of Consult any General Surgeon
for Your Boil on arm which is fast growing within next 1-2 days.
You must have got infection from anywhere You working with any missed injury
As You have not mentioned initial Size of Boil & Current Sizeof boil & exact location of boil. But It must be Infection.
You have not fear of Death.
Just visit Surgeon if It seems You Major Problem.
Otherwise Consult Your near by Doctor.
Ask for Proper Antibiotics & If required Incision & drainage
(I & D) will be needed. But not be panic.
Ask me any question directly.