I have been under a lot of stress for the last 8 months. I also eliminated wheat, dairy, sugar, etc. over two months ago. B12 is found in meat, dairy, eggs and maybe other stuff you've cut out. Recently I have been exploring the possibility that I am B12 deficient. One thing that lack of B12 can cause is asthma. Stress causes your body to use up B12, I think. Google B12 and asthma and see what comes up.
A few things that might help. Take goldenseal. Use food grade H202(has to be food grade), in a vaporizor, the old fashion steam kind. Hops flowers can be bought from herb vendors, boil a big pot of water put a couple handfuls in the pot. Remove the pot from the stove cover your head and the pot with a towel and breath the steam. It doesn't smell to good, but it helps the wheezing and kills stuff as well. Doing a nette pot might help, stuff grows in the sinus and migrates to the lungs.