Welcome to the forum.
You’re boyfriend needs to up his salt intake. That will fix his problem. That is if he’s been staying under 20 carbs daily. Otherwise he’s dragging out carb withdrawal. 2 teaspoons of salt daily or 10 grams taken with food or water. I use those pink Himalayan salt crystals that are like little pebbles and swallow 3grams when I have cramps or headaches. Fix the problem now with any salt.
Congratulations on 13 lost pounds! It’s mostly water but 13 lbs is 13 lbs and I’ll bet you can see and feel that. You should try to up your fat intake for energy. Make sure you’re eating well and aren’t being hungry. KETO at this point is about getting your body used to burning fat and it takes a while before your metabolism gets good at that, we call it being fat adapted.
Make sure you’re both getting 2-3 liters of water and 2-3 teaspoons of salt. Lots of great people here to help, I wish you success.