Muscle pain could be electrolytes, especially magnesium and potasium.
Ketostix can't read amounts people usually make eating more than 50 carbs.

I have hypoglycemia and a rush of bad symptoms when I jump into lowcarb and it takes a while to be able to lower. My symptoms are alleviated around 50 net carbs. I can slowly lower from there. Everytime I feel hungry in the beginning 1/3 cups nuts can help. I'm sure know the low blood sugar drill. You never need as much food as you think you need to turn it around.

It would be very interesting for you to do the glucose tolerance test with insulin levels.