Start by seeing a doctor.
Well, I looked at this thread, thinking I have the same problem.. but I dont.. or maybe I do 0,o Anyway I explained to my teacher that I was practising everyday, alot, ~ said to him.. my fingers are tired.. I struggle to play it right.. but yesterday was fine... ~ I explained how I had had a shower and cooled my hands down.. that helped alot.. ~ but I played through the exam piece.. and he said.. the piece sounded tired, I could hear it to. He got up off the chair 10minutes later.. told me to stop practising and do something totally different.. get out of the house. He closed the piano lid.. told me to stay away. (This happened just 8hours ago)I have a grade 7 piano exam in 5days, the particular problem is playing the ABRSM A3 piece,Presto by Mozart (cant remember K number, and im in bed to tired to want to look.)Now obviously im wanting to practice and its like a knife to the heart when your told by your teacher to stay away. ~ But maybe you should do that to, let your fingers take a holiday, stay away from anything that uses alot of finger work (eg piano, guitar.. PC keyboard etc) fingers take alot of training to become athletic.. but everyone of them needs to rest sometimes.