Pain on top of pip upon finger flex, underside of mcp clicking upon flex (prominent when finger is curled)? knuckle got hit 4 months ago. musician.

See osteopathic dr.: Anytime there's trauma to a finger or toe, it should be checked. Usually it's not just the finger that's involved but the entire hand, elbow, shoulder, neck, upper back complex, depending on the vector forces involved with the injury that needs to be evaluated to stop the clicking. Your finger pain indicates that you need treatment. It may be good to see an osteopathic physician, who can evaluate it fully, and treat you. You may be pleasantly surprised.