Hello dear, The symptoms as mentioned in your post can be attributed to Lower Respiratory tract infection. However, an ECG can be done to rule out any Cardiovascular cause for fluttering of heart. Histatussin cough syrup being an anti-tussive preparation will only help in symptomatic relief of cough. But the underlying cause needs to be treated with a course of antibiotics to prevent recurrence. So, it will be advisable to consult your Physician for proper clinical examination. Investigations like complete blood count, X ray of chest will be helpful. Meanwhile...keep yourself protected from exposure to cold, maintain adequate hydration & nutrition status. Wishing you a speedy recovery. Take care.