Your EKG was normal, you say. You also say you are active and in good health. Certainly seeing a cardiologist might reveal something (blocked arteries?) but might reveal nothing out of the ordinary.

Seeing a counselor (preferred would be a Cognitive therapist or Adlerian therapist) would give you a chance to talk with a professional about your several important losses. You are clearly under a great deal of stress, and you need to talk with someone whose specialty is in how thoughts affect feelings. (Even when you aren't completely conscious of it, you spend time and emotional energy thinking about the two people who died, but especially your mis-carriage. The unspoken thoughts about them become the basis for feelings that result in stress.) Best wishes in this...

--  Dr. Bob, Adlerian Psychologist