I'm 46 & just started playing the tenor sax. Been trying to practice 1 hr a day but around the 45 min mark when I play middle G it gets real pitchy. Tried a different sax same thing. Is this because my embouchure is not strong enough yet, I'm I trying to practice to much, or is it something else? I use a no.2 java reed. I switch to a different reeds when this happens but still a no go & have to stop playing. Please help.