He needs a doctor. Important for him to realize that prevention is more important than cure. These symptoms are worrisome and should be checked to avoid a heart attack, etc. Otherwise, he would need emergent treatment if cardiac disease is missed.
Get evaluated! He needs to see a physician for exam and evaluation for these two serious complaints. Get check early before it turns into something serious, if it isn't already serious. Emergent interventions are dangerous.
Time to man up. If he is worth your investment of time or any long term relationship he needs to prove he can be an adult and address his personal health care needs. Otherwise you face two realities.He has some irrational fears he does not have the skills to deal with and may deal with other stressful situations the same way.He is dragging you into this as a surrogate mother. Either get him some help or move on.