What illness is it and how should it be treated?

Patient's question:

Detailed medical condition and consultation purpose: The child has been coughing for several months, it seems like a dry cough, sometimes with phlegm. When taking medicine, the cough usually stops, but it starts again after half a day or a day. They have been to the hospital, some doctors said it's allergic cough, some said it's poor immunity, and they all prescribed medicine. The most frequently prescribed medications include 'Shen Zhu Li, Fen Nag and anti-inflammatory drugs, etc. But after taking the medicine, it's still the same. I'm worried that the child is taking so much medicine for so long, what should I do now? Please ask the expert doctor for a diagnosis and guidance! Thank you
Previous diagnosis and treatment history and effectiveness: X-ray examination showed no abnormalities, slightly thickened texture

Doctor's answer:

Continue anti-inflammatory drug treatment.
Desensitization involves fasting from certain foods such as meat, eggs, fish, and milk, or taking antihistamines like chlorpheniramine.
Add more clothing in winter, reduce outings, and pay attention to keeping warm and avoiding cold. Be mindful of environmental pollution.
Strengthen the body and root, prevent external pathogens from invading. Herbal medicine can be prescribed for regulation.
There are many causes of respiratory issues in children. If a child is diagnosed with a respiratory condition, parents need to cooperate with the doctor for immediate treatment, including gastric decompression, and develop good hygiene habits. Parents should avoid encouraging picky or biased eating habits in children and ensure a balanced diet.