Welcome to HCM
We understand your concerns
Frequent breathlessness and associated symptoms could be due to lung insufficiency or allergens. You did consult doctor and he told there is nothing medical about it. Then you should be happy and don't worry much about the condition.
Check your place of living and work. Keep a log of arrival of this breathlessness and things you did prior to that experience and maintain it. You should come to a conclusion within a week if there is a pattern.
Start 20 minutes sessions of deep breathing exercise
twice daily to help you exercise lungs and energize body.
Get well soon.