Welcome to Healthcare Magic
You probably have an infected lymph node or abscess
which can cause this among a range of possible causes of this problem. Especially if you have fever
it could be due to infection. There may be infection in the mouth, gums which can cause lymph node infection
. Avoid bad posture at work, use good neck support, avoid wearing tight ties on neck, get enough sleep with proper posture as well. There can also be possible nerve irritation
which can cause this problem. Better to get investigated by Surgeon for proper diagnosis and exact treatment.