Not diabetic, but potential hypo, out of breath at night, odd urine...

So, I guess I'm not diabetic. Still I want to share this as I don't know where to start as the whole thing seems to be too complex for my GP.

Every few months I wake up at night and am completely out of breath. My lungs are free. Often I have the urge to exhale, while each inhale leaves me more out of breath. This condition reappears for the coming 2-3 weeks every night and vanishes in the morning or noon. Calcium citrate powder in water seems to remove this feeling out of breath within an hour. Never had a blood gas/pH test when I was feeling like this due to waiting times in A&E. This breathlessness always occurs after I did something extremely tiresome for the first time, always something related to endurance sport: running uphill for the first time, running again after a long break, swimming 1.5 miles fast, doing interval training with jumping jacks instead of taking a short break after each strength interval, etc. Every time this occurs for the first time again I have to pee a lot several times during that night, and my urine smells odd, kind of like a crate full of old books and clothes.

So, how does this relate to blood sugar? I'm not sure. There are two things that happen for at least 15 years now, maybe for much longer that might be related to low blood sugar.

1. I'm always fairly low on energy in general. My second breakfast needs to be within 90 minutes of the first, otherwise I crash completely: shivering, weak, tunnel vision, no concentration, waxy mask facial expression and extreme hunger in anything sweet. I'm not sure if my blood sugar is low as I only think of eating then, and not of getting a blood test. I continue to feel like this for pretty much the rest of the day even if I eat immediately when this happens. Furthermore my body seems to remember it and the same happens for another 4-5 days at around the same time even if I eat like crazy and leave no long gap between food intake.

2. I've been trying to do endurance training for years now but am not really getting much better, faster or get able to exercise longer. I know in theory how to teach your body how to use fat stores as energy. Yet my body refuses. I can do any activity (running, gardening, walking, outdoor games) for just over an hour, and then the same as above happens if I don't eat some quick carbs. Over the years there has been no improvement in how long I'm able to do an activity. Again, if I crash the same repeats the coming days at around the same time even if I'm sedentary then and eat in time.

So I wonder if this could be related: I put some serious cardio strain on my body, then eat. Then go to bed at a certain time and sleep. Then wake up out of breath. While I sleep I don't add more energy of course while my body is still fighting with the effect of that activity. Energy levels drop big time, maybe blood sugar as well, and then above somehow happens. As with 1 and 2, the same repeats for the coming nights (well, for 2-3 weeks usually).

Blood sugar tests: usual normal when one was taken (not sure if this means 'normal' or 'low' or 'high just over range'). I had two slightly elevated long time sugar tests in the past 10 years, but usually it's low. My glucose levels don't seem to go over 120 within two hours of having eaten. Never saw a really low result either though. But yes, if I crash my brains are so absent that I cannot get a test. I'm nowhere near a glucometer then anyway.

I wonder if some parts of this sound familiar to some of you. I feel it has to do with energy supply and lack of energy somehow. But I'm not sure where to start.