<s>[INST] Two weeks ago I was unwell breathless & dizzy I had had a gastroscapy two days earlier & so medical staff where I was on a day out called an ambulance. At the hospital they said I had an infection bloods showed white cells were raised, they treated me with strong antibiotics. They also did chest & stomach X-rays & abdominal scan, & ECG all were normal. When I came home three days later I was still feeling very unwell mainly due to weird episodes my GP said could be post infection/viral anxiety attacks. I have had another ECG & the t trace was showed abnormalities which they said could be due to thyroid. I had blood test for that but it was negative. At the moment my main symptom is irregular heart beat it doesnt appear to be over 100 beats per min but is defiantly not right. It is like that most if not all the time but I notice it more when trying to sleep. If the t trace on ECG showed this abnormality & its not thyroid what else could it be?? [/INST] Hi, I do care for your concern. The changes in the T waves in ECG are produced by altered levels of potassium in the serum in most of the time but not always. Hence I would recommend checking your potassium level in blood. Consult with your physician and get treated if there is alteration in potassium level. Doing an echocardiogram will also help to diagnosis. If everything normal, then need not worry a lot as this may be the cause for your concern. Hope I have answered your question. If you have any further questions I will be happy to help. </s>