Feeling great all of a sudden hit a wall

hello 4 weeks in carnivore hitting prs in gym feeling great bacon butter beef eggs tiny amount of dairy and mcT oil . the last two days I have headaches which even at my unhealthiest id never get ever . and I'm very tired like energy is super low . very possible from new born baby but I'm getting 8 hours sleep still . salting my food generously and my water intake is like 1.5 l I know it should be more from tomorrow I'm aiming for 3litres . ketones in mornings are 2.0mmol consistent. any ideas why I have hit a wall I supplement magnesium omega 3 and basically Europe's version of lmnt. like I went from yes let's take on the world in week 3 too wow I'm flat af here