I have a very bad cough. i have a hard time breathing in without coughing. i was prescribed a z-pack and mucinex (guaifenesin) d for sinus infection. bronchospasm?

See doc again: If you have a hard time breathing, you need to get checked again and hopefully get a lung function test or even a chest xray. On the other hand, trouble breathing in is more suggestive of obstruction at the upper airway and not the lung. Once we have the lung function and/or chest x-ray finding, we will have a better chance in pinning down the cause. Zpak may not work for sinusitis