Your problems may be suggestive of anxiety
disorder (panic attacks to be more specific). Anxiety is a great mimicker of other illnesses and if not properly recognised, can lead to a lot of confusion regarding diagnosis (as in your case). Consider this example: It is very common to feel tightness in chest and shortness of breath
during tense moments (like before exams), which you might have already experienced. Consult a psychiatrist
for proper evaluation and management. All the best.