Left lower outer chest area with sharp pain radiating to shoulder blade. what is the possible cause?23/m with history of gastritis and tenting of left diap

Likely GI, but...: In general, such a pain does not sound like heart pain, which is what most people would be concerned about.However, young people can have heart attacks. Such things as family history, smoking, gender, other diseases like high BP and diabetes increase the risk.However, i would think musculoskeletal or GI like reflux more likely.Bad pain, worsening, radiation, nausea, sweating or short breath-be seen.

Tietze Syndrome: Tietze syndrome also often called costochondritis in tietze syndrome you get a sudden chest pain radiating to arm or shoulder and can last for few weeks and also has a little swelling at junction of rib and breast bone.Or it may be just costochondritis.There is also possibility od esophageal reflux and gastritis causing your symptoms.