Hi,
If your father is suffering from throat pain then it might be due to
upper respiratory infection or acute bronchitis then he would require antibiotics (quinolones or macrolides or cephalosporins or
amoxicillin with
clavulanic acid) with antihisamines,nebulization and steam inhalation.
Now.asthma is itself a allergic disease due to cold or dust or pollens or grass etc irrespective of the triggering factor.
You can go for pulmonary function tests if not done.
Treatment is mainly symptomatic which might require steroids inhalers,beta receptor agonists,anticholinergics (as MDI or rotahaler) as a regular treatment.
To decrease the inflammation of bronchi and bronchioles,you might be given oral antihistamines with mast cell stabilizers(
montelukast) and steroids (
prednisolone) with nebulization and frequently steam inhalation.
The best way to cure any allergy is a complete avoidance of allergen or triggering factor.
Consult your pulmonologist for further advise.