Since October I Have Had A Fast Heart Rate> I

Since October I have had a fast heart rate> I have as yet not been able to be diagnosed. At the beginning I sometimes would feel numbness on my left arm and tightness in my chest> it was established that I had not had a heart attack but I am nevertheless very worried. when I exert myself I feel a twinge in my chest. I take blood pressure medication and had been doing very well but the BP is a bit higher than normal since the heart rate problems. 18 months ago now I had a severe breathing attack and went A&E where I was stabilised by nebuliser and given a steroid boost. I also suffer with fibromyalgia which I have learnt to live with. in 2007 I had pleurisy which was successfully treated with antibiotics. Could I have serious heart disease. I hoped that I would be given an immediate cardiology appointment but they seem to be relaxed about it all. can you help? Juliette