My sister had a similar problem for quite a while, it was eventually diagnosed to be palpitations (sp?) and the doc gave her some drugs to clear it right up, ask your doctor if it could be this, sometimes self diagnosis is best, I personally, self-diagnosed myself with glandular fever recently, the doctor told me to stop being a hypochondriac, but due to my persistence, took a blood test and it came back positive for glandular fever, so could be worthwhile saying you think it may be palpitations. Good luck!