Electrolyte Balance

Since the transplant, I have been having some minor issues with electrolytes: Na⁺ (sodium), Cl^– (chloride), Mg²⁺ (magnesium), Ca²⁺ (calcium), and K⁺ (potassium). Each lab draw will test for the levels of these ions in the blood. I am going to put phosphorus in there too since they test for it each time as well. Here are my recent results:

Calcium levels have been pretty stable except for the last test. Potassium has been borderline high, and phosphorus has been low quite often. The doctor from the latest call said he was not concerned since the calcium and potassium levels are barely over the limit so I can try adjusting my diet. The problem is I do not know what to adjust. I have not been eating any bananas or potatoes. The only things I can think of are broccoli and maybe nuts (almonds). I need to balance this with phosphorus. Since most foods have both, cutting back on one will affect the other as well.

Previously, a nurse practitioner told me to drink diet soda for phosphates. I have picked up some Coke Zero but I just found this list of beverages and Coke Zero had both phosphorus and potassium. I need to find a beverage where sugar and potassium are very low, but has high phosphorus. From that list, the choices are pretty minimal: wild berry Aquafina, Diet Dr. Pepper, and unsweetened Nestea. Interestingly, Diet Coke has much less potassium than Coke Zero. Maybe it is due to the different sweetener used?