First, you need to write all her symptoms in a diary. Even symptoms you dont think are related. Is she fussy, hard to get to sleep, does her poo smell, any dark circles under eyes, rashes or itchy skin, etc.
Next, you might find that a naturopath might be more helpful. Standard med docs are not good for much.
also, consider an accupuncturist, (ask on the board here) many people claim they cure a vast array of problems.
Whooping cough (pertussis) is a bacterial infection that can last 6-12 months. Most kids are vaccinated for it. I dont know if the live virus is in the vaccine and if it can be transmitted. I do know that the vaccine wears off after about 8 yrs. Me and hubby both had it for 9 months- but kids got it slightly for only a few weeks, they had been vaccinated. Antibiotics only work if you get them in the first few weeks of ilness, otherwise it must take its course. Symptoms are: a seemingly normal person, then suddenly a long string of coughs - to the point where the person runs out of air, and feels like they are gasping. There is a "hoop" sound when the person tries to breathe in after the coughing jag. otherwise the person looks normal.There may be some urine leakage.
Parasitic worms can cause coughing, they can migrate to the lungs. No- parasites are not rare in america!- my 45 yr old freind just got diagnosed with hookworm. Hookworm can enter the foot through infected soil.
Roundworm (several different kinds) can cause coughing. Stool tests can look for the worms and eggs.
Magnesium deficiency can cause recurrent soft tissue infection on the lung/sinus/throat/vagina. (by the way, an upper respiratory tract infection usually connotates a sinus, nose, larnyx or pharnyx infection- commonly from group A strep, or a virus). Many sinus infections are fungal in nature.
Xylitol may help with fungal sinus issues .
More possiblities:
Cystic fibrosis,
renal failure,
bacterial , viral or fungal pneumonia or infection,
congenital herpes,
Cholesterol metabolism condition
Allergies to bird/cat/rodents/cockroach feces
inhaling bromates in a hot tub that has not been properly Ph balanced-dirty
Pesticide poisoning
sarcoidosis
epiglottitis
Eosinophilic asthma - white blood cells in the airways
(ps- the word "asthma" simply means inflammed breathing tubes. A cough with wheezing on exhale is "asthma" - ascarias worms can be one cause)
food allergy, food additives
GERD
Stridor is harsh breathing on inhaling- swelling of upper airways- usually viral
a half T Tumerick in a cup of milk is suppose to help coughs.
A good form of magnesioum to try is babycalm or kidcalm- both found online. or also online- magnesium oil which is rubbed on the skin.