Perhaps you are hyperventilating as you neb? People often try to breathe very deeply to get the solution deep into their lungs. But it's not good to breathe that deeply unless you slow down. I used to do it - my daughter who often used to do nebulizer education in the Emergency Room says "Inhale 1, 2, 3, 4. Hold 1, 2, 3, 4. Exhale 1, 2, 3, 4, 5. Pause 1, 2." It fixed my problem - are you willing to try it?