Welcome at HCM.
I have read complete details of your question.
It looks from your details that you had injury
of your finger about 2 months ago & now you are having problem at your finger joint.It looks that you have not taken care of your finger properly.
Looking at your details there can be infection at your finger joint,there can also be ruptured tendon at finger.
This should be checked by your orthopedic doctor.
At present it needs proper evaluation & a good physiotherapy
Hope this will help you.
With best wishes.