What do I do about my weird weight fluctuations?

I can easily gain or lose 5 - 10 pounds in a day based on my sodium and carbohydrate intake. If you are low on carbs one day, you lose those carbs (glycogen) and there is about a 3:1 ratio of water to carbohydrate in your muscle cells, so in other words, just consuming 100 grams of carbs can increase your water levels by 300 - 400 grams. Sodium also impacts water balance.