I just joined these forums after finding this topic, after searching for ‘kidney pain and keto’. (this comment is for everyone, not just Alpha)
Hi everyone it’s nice to meet you all, and sorry to hear that you’re all having some form of discomfort or another, that sucks!
My kidney pain didn’t start until I began eating a solely keto diet, exercising, intermittent fasting. Up until then I had a really bad diet, high in meat and sugars and energy drinks (I mean 2 or more energy drinks a DAY, coffees, meat in at least one meal but often more), very little water, alcohol, very overweight. I’ve lost a lot of weight and am feeling great, but like Alpha - if I eat red meat now I get kidney pain, it’s a dull ache that can last for over a week if I have even only a few servings of red meat over a week long period. Red meat includes pork, as well as beef and lamb. It’s worse if I bend or move suddenly, like a feel a sharp pang shoot out from the kidney. If I stand very still I hardly even notice it, but mostly it’s just a general dull ache that varies in intensity (never unbearable, just annoying)
What I’ve found also causes it to flare up is coffee (plunger grind, the real organic stuff. The instant stuff doesn’t seem to affect them though I’ve been trying to avoid it). If I have plunger grind coffee (literally just the ground beans steeped in water) my kidney will be sore within a few hours of drinking it, so I’ve cut those out completely.
I have no other symptoms at all, no urinary pain, no change in frequency of urination, just a dull ache that comes and goes and is situated solely in my left kidney (when I first got this a few months ago, it was both kidneys for a few days, now it’s only the left one). I am now eating pretty much only fresh (raw) salads daily, with some egg every now and then, or chicken a few times a week, in an attempt to avoid things that will cause it to get worse again. I’m also drinking a LOT of water, sometimes with lemon sometimes with ACV, sometimes with a bit of baking soda. And celery seems to calm it down for a few hours (though it’ll come back again once the celery is digested). I’ve had to stop exercising for now (I was doing long walks) until I can get this issue under control.
I’m wondering if adding some carbs back in could help balance things out a bit? Maybe some sweet potato, regular white potato, maybe rice? It’s just frustrating because I know that will mess with keto, but I’m truly wondering if it’s the ketones themselves that have caused all this to flare up in the first place? I used to eat meat and so much other crap pretty much every day and while I have 0 wish to go back to that, it just seems odd that now I have to be careful of every little thing I put in my mouth due to worrying about pain, whereas back when I was unhealthy and obese I could eat anything with no issues at all 
sigh
Another thing to note is that my dad has really bad gout, so maybe there’s some kind of genetic weakness to uric acid in my body? I don’t have gout though thank god but I know uric acid can affect kidneys pretty harshly and cause stones too.
This thread has been really helpful though. It’s comforting to know I’m certainly not the only one who has experienced kidney pain once making the switch to keto! I just hope I can deal with it while remaining on a keto diet because regardless of the weight loss, it’s now just my preferred way to eat. 
