I'm a 16 year female with no past medical issues headache-frequently nauseous-fatigue/tired-leg aches-slight loss of appetite-sharp pain in left lower chest(occurred only for 3-4times)-usually sleepy what are these symptoms of?

You need to see a doctor for an evaluation. These symptoms could represent a lot of things, depending on how long you have felt this way. In an acute stage, it could be a viral infection of some sort. If it is more chronic, things like rheumatologic issues come to mind. But, to figure this out, the first step is to see your doctor who knows you best and can do a physical exam and the needed tests.