are u taking vitamins? and getting in plenty of water.
also if your eating alot of red meat try some white meat i havent had the tired feeling actually by day 3 i had energy (but everyones different) i stick to 20 grams max and really havent been taking in that much i have been around 9 carbs up to 18 what would you feel like if you reduced your carbs a bit and didnt go over?
also are you eating the right carbs?
i would say if it persits maybe see your doctor for some advice sorry i couldnt really help you.