I have no idea what to do anymore, I have tried everything i can think of to make my problem go away, from different excersises I have done in the past to help with this with no luck... After I marched in the Memorial Day Parade, my playing has never been the same, notes that I can usually just hit any time I want, won't come out. Notes like C, D, and E on the staff... It feels like I have lost all sense of control on my horn and my tone flexibilty are completely gone. I don't know what to do, I have pulled from flexibilty studies from the Arban's and books of the same, along with scales and mouthpiece buzzing. Just about everything I could think of I have tried with no success yet. However, my range is the same as it has always been... This is very discouraging to me and my practice, I have no idea what direction to go in. Any ideas?