Sounds like liver (vit-A toxicity: sluggishness, fatigue, depression…) might have been your problem too…?
My ability to exercise diminished some at first (as expected), & then only improved with time. My experiment with liver was definitely a temporary step backwards, so I quit that. My progress when running & lifting comes very fast now. I have not had issues with brain fog while eating a liver free & carb free carnivore diet. I have added whole fat yogurt here & there, which has a few carbs & has helped some with gut issues, but it seems to have a negative effect on my skin. I think that’s just dairy related.
Plain coconut yogurt seems like it might be better. And coconut oil on a regular basis appears to be helpful too. While they aren’t really carnivore they are pretty keto friendly.
My reactions to dairy just kinda make me want to avoid kefir. Is there something I’m going to get from that which I can’t get from a high quality live culture yogurt once in a while?