Low Potassium At 39 Weeks.

Hi, has any mummies encounter the same issue as me? Vomitting due to the food i ate the day before and body feel so weak. Hence went to Kkh a&e, dr mention ecg heart rate abnormal due to fast heartbeat and low potassium. Any idea what i should eat or drink as i will be going fot my c sect on 24th nov 😩#pleasehelp #advicepls