As to the tightness in your chest, because
of the overuse
of Duoneb your lungs are probably extremely dry and you may be forming thick sticky mucus. So you really should, not only cut down on the Duoneb, but also get yourself an expectorant. I use over-the-counter guaifenesin. I get plain quaifenesin, not Mucinex.
I am currently working on substituting Duoneb, insofar as is possible, with natural anti-inflammatories, to eliminate side effects, particularly candidiasis.