When I was on low carb for the first time I was so tired I could not function, I was not taking the calcium magnesium and zinc and the Potassium, I went out and bought them, and I started taking them in the parking lot of the store, i felt much better later that day.
If you are losing very fast that can happen too, and make sure if you up your carbs you do it with healthy ones, not the low carb bars or something, the last time I was low carbing those bars kicked me right off my woe. It took me a few weeks to get back on. Also, plenty of water is very very important, look at what happens to plants when they need water, they wilt, we do too, but in a differant way. They are finding that dehydration causes a lot of problems that they did not know about , it is so important to get enough water daily, especially on a low carb diet !!
Congrats on the weight lost, you are doing great and I am glad you are feeling better, it just takes time to get there !! Stephie