I`ve been playing euphonium for about 3 years now, and took trumpet up about 2 years ago. I`m grade 4 on trumpet and grade 3 on euphonium and taking grade 5 on both this year. Previously, the playing of the two instruments has had no effect on each other. But recently, my trumpet playing has deteriated a lot, most notably i seem to lst the ability to slur to notes lower than middle C. Any suggestions people?