"Harm" does not solely mean "something that costs money". However, it would need to be equated to money.
Using my earlier example of losing an arm, surely we would all agree that there is a "value" to the lost arm. The exact amount would be hugely contingent upon the person's age and what they did for a living. If the person was a 25 year old professional football player, that arm could easily be worth ten million dollars.
Conversely, if the person were 85, retired and dying from some unrelated issue, the arm would be worth much less, perhaps $50,000.
So yes, pain could certainly be considered harm. A good example is a personal injury lawsuit arising from a car accident. The person may have no visible injuries but might suffer from constant neck or back pain. This would certainly constitute harm and would be the basis of a viable lawsuit.
As to your questions regarding a hypothetical surgery, the answers would depend on several factors. First and foremost, you would need to be able to attribute the surgery directly to the doctor's missed diagnosis. In other words, you would need to prove that, but for his diagnosis, you would not have needed the surgery. If you could do that, then yes, you would have a viable lawsuit. In that event, his insurance would likely cover all of your related medical expenses as well as providing compensation for all related issues.
Also, several customers have asked how they may direct a question to me in particular. If you specifically want me to assist you in your legal matter, just put "FOR JOSEPH" in the subject line and I will gladly pick up the question as soon as I am on-line.