I feel pains in the upper left part of my chest, feel tired within short times and feel a little dizzy. What should I do?

See a doctor. These symptoms may mean a serious condition, either in heart, lungs, or both. I would get evaluated right away.
See your doctor. You will need a more thorough history to be taken, an examination and some tests to figure out why you are feeling that way. It could be anything from dehydration, to heartburn to flu to something more serious...
Worrisome. Chest pain, easy fatigability, shortness of breath (not sure if you reported that?), and dizziness: if they're all occurring at the same time is potentially worrisome. You should be checked right away:family doctor or emergency room.
See Dr. Chest discomfort, dizziness and tiredness are very common symptoms but we have to characterize them and pt needs to be examined and needs lood tests to know the diagnosis and propose a treatment. We have to rule out, cardiac disease, coronary heart disease, arrhythmias, poor circulation, inner ear disease, anemia, dehydration, congestive heart disease, etc.