The first dentist was correct in my opinion, and the second dentist was also trying to help--and needed more information about how the pain started and when.
Here is why: you had not problems with facial chronic pain before you had the filling done. It sounds to me that you may have had myofascial pain dysfunction, a muscle imbalance causing pain. Also, your "high" tooth may have been irritated.
If the second dentist wanted to maintain what we call "vertical dimension" of the occlusion in dentistry, this was to help you. If you had told the second dentist you were good before the filling was done, he/she may well have suggested the reduction of the high filling. In any case, it's your decision, and you seem to have had the correct answer all along, which is: grind down the filling to match your other teeth. This is the answer.
If the second dentist won't do that, then they may think you have loss of vertical dimension, which is a completely different topic, and one which has little to do with your high filling. In that case, you would have needed to see a different, third, dentist where you could get what you wanted done.
Of course there is another unmentioned thing: why was the filling high in the first place? In my practice we always check (with a checking carbon infused film) if a filling is high. Every time. That takes time, and protects you from what happened.
If the filling continues to be high, you might have increased problems, so it's best to act sooner than later.

Stuart Smith