Weird feeling in right thigh during prolonged fast.

Hello everyone, I’ve been reading this Subreddit and posts with similar problems, but never quite the same as mine.
To the point.

Around day 3-4, my right thigh starts to “ache”. It’s always the same area, the same leg and the same kind of feeling. It feels like I should be able to “stretch” it out or maybe massage. Kind of like a knot. I’ve seen the electrolytes’ wiki here, and it seems I’m dosing correctly, but it still appears.

By looking at an anatomy picture of the thigh, I’d say it might be the Vastus lateralis or perhaps Tensor fasciae latae (both are near the side of the thigh and at around 1/2 height).
It’s probably the only thing that’s keeping me from going a lot longer because it’s intense enough to distract me from work and things I enjoy doing in my free time.
It doesn’t seem to matter if I exercise that day.

My daily intake of electrolytes is around 7.5g of himalayan salt, 8g of potassium chloride (KCl) and around 600 mg of magnesium chloride (the box says MgCl2 x 6H2O) + a multivitamin which has vitamins as well as potassium and magnesium (not that much, though). I mix 3.6g salt + 4g potassium chloride + 300 mg of magnesium chloride per 1l of water.

Now the weird part:

The ache seems to go away for a small amount of time if I drink some of my electrolyte mix BUT give it 10-30 minutes and I need to rush to the toilet to urinate, and the thigh starts to ache again. Even if I sip it thorough the day I can only calm the ache by drinking around 400-500ml of the mix, rush to the toilet, and I’m back at the start.

I will be terribly thankful for any input. I, myself, ran out of ideas.