You can try steam inhalation.
OTC Anti allergic medication like cetirizine can be helpful.
Still if you have wheezing or asthma like symptoms you may have to visit your doctor for prescription of inhalers etc to control the symptoms.
Breathing problems you describe are classical sign of allergy.
If their was dust previously chances are that it cause some inflammation in respiratory tract and symptoms are taking time to heal.
And yes glass fibre insulation can also be the cause of respiratory allergy.
Usually allergy subside when the exposure to allergen is stopped.
If the glass fibre insulation is causing respiratory allergy medications can stop symptoms in short term.
But long term exposure can cause inflammation of respiratory tract and patient develop allergic bronchitis.