Please hang in, eve. As already said, it is a process; it is not fun but we have to get through it to reach the other side.
Be very good to, and gentle with, yourself. Stay well hydrated; get plenty of rest; take in some fresh air; try to get some light exercise - even a short walk can help; take some warm, aromatic baths; have light and healthful meals.
You may want to schedule a check up with your GP and have some blood work done to make sure your levels and values are okay.
It is normal for brain fog and fatigue to last a while but they WILL improve. Be patient with the process; sobriety and recovery are worth every bit of discomfort. I swear.