Tomorrow? And you want us to cure what you developed over time? ok.
Do this, go outside, get you a throwing partner, stand about 20 to 30 feet apart, now don't do anything except just toss back and forth and practice the release at slow speed...follow through with the mechanic, but the idea is just get to re-feeling the pitch without any arm impact. Feel your grip, feel your release..visualize, fastball behind, curve up front, relax, you will find it, work it in your bullpen and in between innings, important not to press or over-throw it, just throw it through the catchers glove and be positive, remember every pitch won't be perfect but the less you press the easier the pitch will come to you, have fun!