Based on details you seem to have viral fever
,with chest infection
probably viral broncho pneumonia and irregular heart rate
and breathlessness suggest to rule out cardiac involvement or low blood oxygen saturation
(hypoxiemia can produce irregular heart rate and breathlessness.
You should consult general physician immediately for clinical examination and you may require chest X ray, 2D echo and ABG to confirm the cause of breathlessness.
I hope this will help you