This often happens during really fast songs, but just on my left hand. I figured that there are some piano exercises that might help to improve my ability to play fast, because it sounds really weird to have my right hand playing perfectly and my left hand lagging about 15 notes behind!
When you practice fast song – start slow, then increase the tempo slowly. Very often the hands hurt because your fingers have not built enough strength to handle fast passages.
Some piano player plays too fast and their hands get tense.
Make sure your wrist is totally relaxed (important)
Before you start fast passages, try slow movement first. Our hands need warm-up just like the body needs warm up and stretching before exercises.
You may do stretching or warm up exercises. Those arm and elbow stretches that are used by tennis or golf players are helpful.
Hanon and Czerny are good exercises – but I would not start them in the begining of any practice session, do that later on so that the hand can warm up with slower passages first