If you are young and occasionally get sharp stabbing pains in your chest while breathing in that go away and have no other symptoms you should tell your doctor of course but also learn about Precordial Catch Syndrome

Precordial catch syndrome (PCS) is a non-serious condition in which there are sharp stabbing pains in the chest. These typically get worse with inhaling and occur within a small area. Spells of pain usually last less than a few minutes. Typically it begins at rest and other symptoms are absent.

Learning about this greatly reduced random anxiety for me. And it stops when you get old yay!