Your description suggests that you have what is called a coronary artery fistula, with a left to right shunt, as you indicate, from a high pressure to a low pressure system. This causes increased blood flow through the pulmonary arteries, increased work of the right side of your heart, which is normally designed to pump against low pressure, and ultimately elevation of the pressure in the circulation of the lung called pulmonary hypertension. In some instances of left to right shunts, the normally low pressure pulmonary circulation can rise high enough to reverse the shunt and remain high permanently.
Clubbing is but a sign of a number of diseases including, but not limited to, lung cancer, chronic suppurative infectious lung disease and cyanotic heart disease that caused blueness of the fingers and lips, and with rare exception, not seen when the abnormal blood flow is from the left side of the heart to the right side of the heart. Your clubbing would appear to be due to congenital heart disease. The key question raised by the presence of clubbing would be is there yet another abnormality of the circulation in addition to the coronary artery to lung circulation flow through which low oxygenated blood is flowing from the right heart to the left? If so, it would be most important that this be identified and a plan formulated to address it surgically, prior to any heart surgery.
Yes, as described, your condition is probably very uncommon, is a potentially life threatening problem and should be treated only by a cardiac surgeon, greatly experienced in the surgery of congenital heart disease. If you have not been evaluated by a cardiologist and a heart surgeon, you should be so evaluated at the earliest feasible time depending on insurance and your other finances. Treatment of your condition is not an emergency but the less delay the better.
Good luck.