It sounds like you are having palpitations—the sensation of an abnormal heart beat—which should be evaluated by a physician. Brief periods of abnormal heart beats (one or two beats) may be a normal variant, but long and painful palpitations suggest an underlying problem with the heart rhythm (arrhythmia) that should be investigated.

There are a number of factors that cause palpitations and can be easily corrected. Abnormal blood levels of electrolytes (potassium, magnesium, calcium), low blood counts, and thyroid dysfunction can all cause palpitations; as can certain drugs, including but not limited to  caffeine, alcohol, tobacco, pseudoephedrine (Sudafed and other decongestants), albuterol, theophylline, and thyroid replacement.

Call your physician’s office to inform them of your symptoms and any medications you may be taking. Schedule an appointment with your physician as soon as possible, and in the meantime drink plenty of fluids, and avoid caffeine, alcohol, smoking, and decongestant medications. If you experience chest pain with palpitations, you should be evaluated in the emergency room while you’re having symptoms.