I think he needs his thyroid checked.
It sounds to me like he may have a respiratory problem, either bacterial or viral.
This would cause him to feel weak, have a fever with tightness to his chest.
I suggest you take him to your doctor to check out his lungs and run tests for any respiratory disorder as well as for asthma.
I presume that when he had his heart checked out and found nothing wrong they also ruled out angina pain?
Hope you get on OK
Does it just feel hot to him, or is it hot to your touch? What does his heart rate and blood pressure do during an episode? Has he had an EEG?
You could ask about dysautonomia, which might be able to cause those symptoms, especially if he really is hot to the touch. Inappropriate shunting of blood to the extremities/skin could cause feelings of weakness, faintness, and maybe pain or shortness of breath from things suddenly not getting enough oxygen (because all the blood's in the skin).
Has he had more than one of these? If you're worried about heart problems, but things are intermittent, they might do a Holter monitor, which is a 24 hour (or longer) EKG monitor.
Those are all the ideas I have for now. Best of luck. Your email doesn't display, it's automatically censored.
Since you live in Arizona, a state I go down to frequently, and since the heat is on with the monsoon season, it also fits heat stroke. It could be, at least 30 conditions I can think of. Is it possible for you to go to a different doctor? One wlso has to look at circumstances and conditions of living, and that can only be achieved with a thorough medical history, along with the physical exam and other diagnostic work up as needed. Also, you can get the chart to look up what they ruled out or considered in those 13 hours you were there. All you have to do is call the hospital, tell them you want the chart on the hospital visit or office visit you did. I investigated my sister's hospital stay doing exactly that because I was only getting a glossed over answer from the doctors, The chart and medical records wss more thorough and cleared my puzzle. Your husband needs to give permission. You don't need the doctor's or hospital's permission.
Has he been checked for Valley Fever?- so common here in AZ