The coughing might be a natural result of the nebulizing with Lobelia causing you to try to bring out some of the gunk in your lungs. You might try getting some mullein extract and using 5 parts CS, 1 part Lobelia and 1 part Mullein. Mullein is both anti-spasmodic and anti-inflammatory. It surely does work wonders for coughing and restricted airways when you smoke it in leaf form - as counter-intuitive as it may sound to inhale smoke in such situations.
Two suggestions:
First, take colloidal silver orally as well as using it in the nebulizer for an even greater boost - and given the difficulty you are having beating the bug I would highly, highly recommend usinjg a top quality colloidal silver, such as the Advanced Colloidal Silver Luella and I both use.
Secondly, get some of the wonderful Chinese herbal formula ClearLungs Extra. Plentiful echinacea extract (oral) can also be very helpful in knocking out a persistent bug. The combo of oral and nebulized CS, lobelia, mullein and ClearLungs has worked fantastically well for both myself and Luella.
I hope that helps!