Game problems

Hi, I'm the one who asked you before about how to play against players! Today I had a very difficult match, I played beautifully until round of 16. I had to play against one of the winners of last years. I got the first game 11 to 8. Next game I was 10:8 up and I had to play the serve. I played two good serves and they caused two beautiful lobs but I missed both of them. I don't know what happened to me! If I won that match I had won my next matches because I knew how to play against them and I could become first. After I lost that match I had to play against a very weak player. I won the first game 11 to 4 and the next game 11 to 5. In the very first moment of the third game his coach objected because of my services. The judge asked another judge to observe our game. During the third game I got disappointed and I lost other games. I don't know what happened to me but I was completely disappointed. Please tell me what to do about my first match when I was 10:8 up and about the second one when I got disappointed because of nothing. I have another question ,too. I'm so good at starting the attack on down spin. I can start on any kind of down spin but I don't know how much I should use this ability to play against players. If I want to attack I play a short service and I start my heavy top spins. After each match my friends told me that I use short services very much and this is not good. Please tell me how many times I should play short serves!