If I can add to what others have said, if you're new to low carbing, it also takes your body a little while to adjust to the new foodstuffs it has to digest and deal with - and the lack of things it was used to.
I felt pretty horrible when I reduced my carbs still further - even though I've lived on moderate carbs for over 20 years, so it perhaps wasn't as big a shock to my system as it might have been to yours, if you'd been a high carber before diagnosis. So maybe ease back on some of the changes and take it more gradually to allow your body time to adjust. Your BG won't come down as quickly, but that's not necessarily a bad thing either, as it needs time to adjust to new BG levels too.
That in itself might be some of the cause of your discomfort, if your BG levels have dropped quite fast, that can also make you feel rough until your body adjusts to the new levels and it panics when it thinks you're running too low, just because you're lower than you were.
I too don't 'high fat' it (as in my sig.), but I have replaced some low fat foods to full fat ones, like butter instead of low fat spread - but I'm not eating as much stuff to spread it on, so probably haven't added many net calories. I too had my gall bladder removed, so for years I couldn't tolerate foods like eggs, but once I reduced carbs, I found that I could now manage them, although I can still only eat one egg in a sitting and have found that I can only tolerate grass fed butter for some reason. You just need to find what works for you.