The fowl taste may be from acid reflux. So I am thinking the whole problem could be acid reflux. Many people have acid reflux without the stereo typical symptom of heart burn. It is commonly miss diagnosed as asthma. You can try some OTC treatments like Prilosec or Zantac. Also, do a quick search on life style changes that help acid reflux - not eating within 4 hours of going to bed, raising the head of your bed 6 inches, avoiding caffeine and chocolate...
I pray that you find answers soon.
Have you seen a Pulmonologist ever or is your GP managing this "asthma?"
Has allergies been ruled out as an underlying cause of your problems?