It is the potassium/sodium the reason of the painful pumps, as a bodybuilder that shouldn't be happening.
Make your carb source potatoes or sweet potatoes, i think that a kilo of potatoes is around 170g-220g of carbs and 4,500mg of potassium (correct me if I'm wrong please)
Sweet potatoes are less carbs but have more minerals in it.
You can makes shakes also, pineapple with spinach, spinach is the food with the highest amount of potassium in it and is dirt cheap, taste horrible, blend it with pineapple.
Remember that potassium is key for your digestive system and keeping a healthy thyroid, it will improve bowel movements on a daily basis.
It helps with your blood pressure also.
Improve pumps, strenght and stamina, nothing better than a hydrated body, right?