Carbs too low??

There is no dietary requirement for carbs.  None.  Zero.

That said, hair falling out and your other symptoms sound like a thyroid issue.  I shouldn’t be armchair diagnosing anything but I would advise you to see an endocrinologist.   There are also several nutrient deficiencies that can cause similar symptoms.

Sometimes the mistake people make when they go keto is in not getting a wide enough variety of foods in their diet.

I eat up to 5 grams of net carbs per meal, and usually get that many by eating green leafy vegetables instead of sugary foods like milk, carrots, or other root vegetables. I understand that we need some carbs, aka vegetables, to get micronutrients, including potassium, which is very important in a keto diet.

I agree with AlohaBird about asking a dr. I also wonder if you have been getting enough B vitamins, which can come from carby veggies.

You may have needed more salt. A lot of people have low salt issues when they limit the carbs to the 20 or so recommended for keto. When you go very low carb your body flushes out a lot of salt and it needs to be replaced along with the attached potassium and magnesium. Most find that adding in a good salt like the Celtic Sea Salt and the Redmonds Real Salt will help a lot.