Have you resolved your cold issues? Are you drinking enough fluids and eating well now? Sometimes with a cold and/or fever you can get dehydrated and your electrolyte (sodium, potassium, chloride and CO2) levels can get off and make you feel dizzy and off. This can cause palpitations if your potassium is way off for example. But usually that happens with a bad flu not a cold. You could get dizzy and/ or vertigo from an inner ear infection. But usually not palpitations. So if your symptoms have resolved other questions are do you eat a lot of sugar, or are you diabetic? Do you drink lots of coffee or caffeine? Sometimes if you have a minor arrhythmia these things can trigger them. So cutting back on the sugar and caffeine will make you feel better. If you want to check if you have an arrhythmia, you can get an EKG, if negative get a 24 hour monitor and a echo-cardiogram done. The EKG takes a snap shot of your heart rhythm and would show a big problem at the time. If it is negative and the doctor didn't hear anything with the stethoscope then the echo-cardiogram can look for structural abnormalities and the 24 hour monitor looks for arrhythmia's.
Also, you can have your ears checked by an ENT.
Do you get off balance or vertigo where the room is spinning?
Regards,
mkh9