Go to ER or call EMS
First of all, if you are "in trouble", or "in extremes", the care must be immediate.
If you are alone & can't breath, 1. Get help, 2. Use the treatment that has been recommended by your doctor, 3. Get to the hospital via ems to get help, if necessary.
The treatment plan you develop with your doctor should include details about what to do under all conditions & should include advanced directives.