Sounds like you might have asthma. I'm 26 and didn't seem to have any asthma problems until I was 24. I was told by the doctor that you don't have to be born with it, it can develop at any time. Talk to you doctor about your concerns. He started me on Singular once daily and an albuterol inhaler. This is working great for me at the moment.
Your symptoms are often associated with anxiety but can also be a sign of lung disease or pleurisy or even disease of your vocal cords. It could also be related to your work in the foundry. You should have a chest X-ray and be examined by your physician. This is mainly to be sure you do not have any serious lung disease. It would be best to be examined at a time when you are having symptoms.