Smoking and not eating can certainly cause lightheadedness and nausea. Other causes of this can be an infection, dehydration, pancreatitis, anxiety, gallbladder issues, reflux, etc. I recommend that you try to cut back and ultimately stop smoking, be sure to eat a healthy well balanced diet, drink plenty of fluids. If your symptoms persist, worsen or you develop other symptoms then you need to see your doctor for further work up.
I am a hypochondriac and always think im dying, is it cancer
No this does not appear to be consistent with cancer at all.
I would not worry about cancer.
But do stop smoking for that is a risk for developing cancer.
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