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You have enumerated too many complaints , but have not said anything else! - you did not mention even your age, or gender; habits or family history and so on....
The complaint also needs further descriptions to suggest the line of approach.
From you say, only wild guess is possible!
You have to investigate your heart, lungs, stomach and nervousness
ECG, routine and exercise / X-ray chest and spirometry
(lung function test) / endoscopy
- are some of the things to be done - to exclude or confirm the suspicion.
Instead of Emergency, you should see an Internist. He will be able to guide you with the best approach and treatment.
Wishing you speedy recovery