Hi i have sore on my hand finger joint for months because of repetitive work i did at the meat factory. is it serious? how to treat it?

Repetitive hand activities, especially assembly line work, puts you at risk for injury. Since this is unlikely to spontaneously resolve, see a hand specialist, and evaluate injury to joint or tendon. This can be reversed in most cases.

As you were working in a meat factory i would be concerned about abnormal infection or foreign body preventing the wound/sore from healing. ORF is an example of non-healing skin infection caused by a virus usually from lamb that causes sores. Seek care.