Hi,
The symptoms you are referring to are related to overload and
stress you are experiencing recently.
I usually advise my patients that "bad" habits like
smoking can't relieve your stress. Instead, deep breathing, or fresh air can help you cleanse your mind and make you think better over the things around you.
Please understand that being positive and wide-broad thinking over things is better than a cigarette. Although you might face an obstacle for the time being, remember to keep on, because you will find the solution later on.
Can go for ECG and heart echo, but before test I'd suggest not to smoke, drink caffeine or energetic or alcoholic drinks to avoid false results.
You are too young to have health problems, and too young to surrender to the obstacles of life.
Keep on being positive, strong-willing and determination to live your life as a precious gift! I know you can do it!
All the best!