Yes, sounds like the typical sodium depletion. It's supposedly a temporary result of all the water lost as you burn off the stored carbohydrate in your body, but I'm not convinced it's all that temporary. Maybe my kidneys are just shot, or I was meant to live near mineralized water and nutrient-rich soil, but I readily and easily deplete of electrolytes in a matter of days without some strong source. My go to is a tbsp. of blackstrap molasses stirred in water, and 3/4 tsp. of baking soda in there, too, on bicycle/sweating/heavy-lifting/cramp days.
Is your pulse a little high? When mine speeds up (while resting) I know I'm low on salt.
Also, some recommend drinking less water to help the body retain the minerals, but I have yet to master that.
Steak, eggs, potatoes - fruits, nuts, berries and forage. Coconut milk and potent herbs and spices. Tea instead of coffee now and teeny amounts of kelp daily. Let's see how this does! Not really had dairy much, and gut seems better for it.