Symptoms are feeling heart flutters, feeling cold and feeling exhausted all the time. what could this be?

Many possibilities: Could be a heart rhythm problem, thyroid abnormality, infection, or other condition. This requires a good medical evaluation looking at all systems and testing to at least include a, ecg, complete blood count, a metabolic panel, thyroxine and thyroid stimulating hormone testing... And others if suspicions occur. Good luck. Er.