Pericarditis is the inflammation of the pericardium, the sac-like membrane surrounding the heart. Pericarditis can causes sharp chest pain due to the irritation of the inflamed pericardium.
Difference between pericarditis and heart attack: Both have sudden and severe chest pain. Chest pain in heart attack can travel (radiate) much farther to left arm or jaw. Duration of pericarditis chest pain can be hours or days. In contract to heart attack, chest pain by pericarditis worsened in deep breathing, and lying down or at supine position. Pericarditis also has other symptoms such as dry cough, fever, leg swelling (caused by heart failure).
Please to go see your doctor right way for diagnosis and treatments if there are above symptoms, or any sign that concern you.