Hi Welcome to HEALTHCARE MAGIC..
I have gone through your query and can understand your concern.
Your symptoms suggest that you might be suffering from Angina /
heart attack. Main cause is coronary artery disease, However it can arise from
anemia, abnormal heart rhythms and
heart failure. You will have tightness in chest, difficulty in breathing, pain in left side of chest radiating in hand or jaw.
Also you have breathlessness during sleep or lying done, which is also symptom of
heart disease.
Sublingual intake of nitroglycerine/
isosorbide nitrate (Sorbitate) should be done in case of severe pain
You should visit a physician/ cardiologist an ECG or ECHO would be done. Don't take this problem lightly.
Hope your query is solved
Get well soon