I experienced shortness of breath while working out with my trainer yesterday (which never happens) and had to terminate the workout early. I then walked to my car with difficulty becoming very tired and out of breath. When I got home, I checked my BP a

Get evaluated now. You are describing something that could be serious, even life threatening. Please call your doctor and go to the emergency department or urgent care clinic right away. You need an exam, an EKG and possibly blood tests or an xray to evaluate for heart or lung problems. Do not wait until tomorrow, go right away. If any chest pressure or pain, call an ambulance.
Shortness of breath. If this was an unusual bout of shortness of breath during your customary workout, it may signal the need for a cardiac evaluation which includes an exercise stress test conducted by a cardiologist. If this reveals no abnormality with coronary circulation or heart function, then pulmonary function testing would be indicated. Definitely discuss this episode with your physician who can also check you.