Why won't my puppy come when I call him, and he acts scared of me?

I have a yorkshire terrier puppy who is 6 months old. He has been very difficult to house train, and I have had to discipline him for it- usually I will flick his nose or smack him and yell “BAD DOG”... I then take him outside immediately afterwards. Since then, he won’t come to me anymore, and acts like he has hurt feelings or is pissed that I had to discipline him. Now, if I approach him whether outside or inside, he will get nervous and just PEE EVERYWHERE!!! I can’t scold him for peeing if I am making him nervous now can I? I just feel as though my dog is scared of me, and I don’t know what to do. I haven’t smacked him for peeing in a long time, but it’s like he still remembers. Will he ever out-grow this? What do I need to do so my dog will trust me, and come when I call him?? I don’t see the point in having a dog if it’s just going to run away from me all of the time, and pee when I pick him up or approach him. I’m sooooo frustrated! My husband says he can sense that I am annoyed that he doesn’t come when I call him, so it’s making the problem worse. This is the first dog I’ve ever had, so I guess maybe I am doing something wrong. Please help!!