Since you have a strong family histroy,you must seek a second opinion.E.C.G.is not the conclussive test.This test under resting conditions may not show anything and is only an eye wash.You must have a brisk walk or jog a bit till sweat breaks out and immediately have the E.C.G.done.Then only this test will show,if there is any thing wrong.Better go in for Tred Mill test (T.M.T.) where b.p.fluctuations along with certain other data is also recorded under stress.Stabbing pain or sequezing pain for a few seconds or a minute or two which goes away on rest indicates more towards a cardiac problem.Pain lasting much longer,could be an hour or more and not responding to rest is more likely to be due to hyperacidity or formation of traped gases.So go to a cardiologist and not to a G.P.for early diagnosis.