When should I seek medical attention for a finger injury?

Deformity-nonhealing. One should seek medical attention for a finger injury when there is a deformity, severe pain, or non-healing (i.e. Symptoms are persistent.).
Look at your finger. If your finger is very swollen, not straight or you cannot bend or straighten it , you need to be seen. Some injuries are best seen in the first few days to get the best results any open finger wounds are best seen asap because of the possibility of infections which could get into the tendon sheaths. So if any question, get examined before its too late.