Thanks for letting us know your medical history in brief.The symptoms are not due to crohns disease
The symptoms of chest tightness
, shortness of breath
are due to bronchial spasm
due to the dust, which is allergy induced asthma. The feeling of heart pacing more than asthma is because you are panicked about your inability to breath . Heart rate of 90/min is nothing to worry about.
1. Avoid further contact with allergen which is dust in your case. ( dust and pollens are the most common allergens)
2. Since you are a known asthmatic you might be having some aerosol spray with you. Otherwise take a bronchodilator
spray like salbutamol metered dose inhaler( MDI).
example:Asthalin MDI : 2puffs thrice daily for 5 days and gradually taper the frequency then stop)
3. In case a plain bronchodilator spray does not help you may need a steroid spray like budesonide example: Budecort MDI 200mcg: 2 puffs twice daily for 5 days then once daily for 3 days then stop.
4. Oral medications like doxofylline and montelukast are prescribed after consultation if breathlessness persists.