My Dad who is 43 years old told me that last night after eating he walked to the living room and sat down on the couch when all of a sudden he got very dizzy then his chest tightened up and he started having a hard time breathing it scared him enough that he jumped up and headed for the phone to dial 911 but as soon as he jumped up and walked two steps it stopped suddenly and never returned. He felt no other effects afterwards. My father is very active and works a manual labor job he is taking Naltrexone (for alcoholism) and Lisinopril (for blood pressure). I am an EMT and the only thing that came to mind was possibly an air embolism or pleurisy but after researching both they seem like kind of a long shot.