There are two supplements that are supposed to be good for the lungs. One is a NAC(N-acetyl-cystein), an amino acid that is reportedly helpful with lung conditions. And the other is Taurine, either ingested or inhaled(via a vicks steam inhaler), helps reduce inflammation and rebuilds the lung tissue. Besides those two supplements, you might do well with Vitamin C and Hylaronic acid as they are also good for inflammation and rebuilding the lungs. In addition to the supplements you might want to try getting a breathing exerciser(just use google or yahoo), helps build lung capacity and strength.
I hope those suggestions help. I know that Tony has already pointed out a number of good herbs that you should try, so I think you are in good hands in that department.
For bulk of these supplements you want to try a place like: Purebulk.com, I get most of my bulk aminos and vitamins from them or Iherb.com if you don't feel like taking the supplements in powdered form.