I Have Had Chest Pains For About 10 Days Now,

I have had chest pains for about 10 days now, I went to the A & E last Saturday and they kept me in for 48 hours. ECG's where normal, blood tests came back fine as did the Chest Xray and my Cholesterol test? I am booked in for a 24 hour heart Monitor to be fitted next week. The Cardiologist believes it is not heart related. But what can it be, I still get them daily and they are at times really severe?