May sound weird try doing some yoga or slowly sipping something cold or listen to calm music even.
Sometimes I watch T.V to calm myself down.
You may want to talk to someone about what is making it hard to breathe like if you are scared or exited.
Or not sure if this is correct but bring it up with your docter, Maybe you have asthma,I have asthma mine is serious
i have the kind that is activity and allergy enduced.
Sometimes when you bring things up to your docter they tend to think about it more.
And what you were descirbing is what symptoms you would get with asthma.
Research online about asthma.
Can't hurt to be well rounded even if it is'nt.

bye,
anon.