This may be asthma. I would suggest
discussingDiscussing death with children this with your physician and/or seeing a lung specialist (Pulmonologist). After a good examination and a lung function tests, the diagnosis should be more clear and so should the therapy.
Next time you have a shortness of breathe get a bowl and fill it with how steaming water and put a towel over your head trapping the steam and just breathe the steam in. This may help as it does for me when i get bad asthma. Another thing is to stay calm.
I know it is really frustrating being like, fresh air may also do you some good even just keeping the window open. By the way do you couch because you can't breathe? Like the couch is opening up your lungs? If so you probably have asthma. Also sometimes inhalers don't work for people. I hope this help although i would recommend trying the steam it isn't gonna solve anything but it may help you to breathe.