Sorry to hear of your divorce. That is got to be the biggest stressor in life that there is.
I would go to a general practicioner because they would be able to direct you to the proper specialist. Or they would be able to diagnse the problem themselves. Alot is also dependent on your health insurance. I think some insurances require a gate keeper physician. One central doctor who refers you to different specialists as necessary. Sorry you're not feeling well, that out of breath stuff must be pretty scarey.