I have only been playing 2 and a half years so maybe problems like this are normal. but in the past, strange problems I have had have gone away within 2 weeks or so. but this particular problem doesn't seem to be fixing itself at all. Up until recently I was able to play comfortably up to the F on the top line of the stave. But in the past month or so, my range has been decreasing and now it is a real struggle to play anything above D (the 2nd last line). I cant find any logical explanation for it as I haven't changed anything about my technique. My breath just seems to be not travelling through the trumpet. It is really pissing me off because it seems to be happening for no reason. I definitely have not been doing anything differently. Any ideas?