Had sex last night, afterwards started getting this extremely sharp pain in my stomach&tail bone area, &i had chest pain(like some1 sitting on me) help?

Sounds muscular: Sharp pains typically represent pain when inflamed tissue is moving (like chest wall/abdominal wall ). Symptoms described as heaviness ("someone sitting on chest") could relate to cardiac causes but could also be due to respiratory difficulties (ex asthma), as well as stress-anxiety/hyperventilation symptoms. Additional history and exam are required. See your doc if it continues.