I have bronchitis & don't want to cough the mucous up, tho i'm short of breath. i try not to cough, makes me gag. what happens if i don't cough it up?

Short of breath: If you're short of breath see an MD get your vitals taken. You may need a short course of antibiotics some cough suppressant with dextromethorphan/Guaifenesin to thin the secretions and an inhaler +\- steroid taper if determined you have hypersensitivity in airway. X-Ray indicated if you've spiked a fever of over 100.4 and have shortness of breath. Good luck.