I could go into some huge rant as to why you have a scratchy throat (I'm a vocalist), but I won't. Basically, the real issue is that you need to breath low and deep from your diaphragm, don't scream, drop your jaw and open your throat. A good way to think of that is to pretend you have a golf ball in the back of your throat and you have to keep that space opened up to fit the ball. Also, don't reach your chin out on high or low notes. If you are going high, keep your chin DOWN and if you are going low, keep your chin UP. Doing the opposite will put excess strain on your vocal chords (as will doing the rest of what I told you incorrectly). If you are experiencing pain or any kind of unpleasantness, then you are doing it wrong.