My breathing seems shallow and it's harder to breathe sometimes. Real or imagined?

Can be asthma, etc. It depends on the circumstances and setting in which these attacks occur. They might be panic attacks, where part of the therapy is to breathe into a paper bag to slow brreathing down and relax. It can be an asthma attack triggered by a thing like cold air. It might be a heart attack. It would help to see your doctor to pinpoint the cause.