Potassium rich foods
Include bananas as you said, citrus fruits including oj, potatoes, tomato sauce/paste including ketchup, and squash.
Medicine will need to be given by your doctor since potassium
otc is suboptimal to do the job due to the need for a higher dose and need for blood level frequent check. There are meds and water pills that your doctor can use to boost your potassium level too.