Hi believe!
That one is hard for me to answer. Maybe Lisa or Tofi or another long termer might have some better input. However I'll try my best.

If you feel bloated it might be that you suddenly introduced more fiber rich veggies. Fibers ARE great, however they could cause bloat if you're not used to that level.

I personally don't think your added 5g carbs from veggies would spike your insulin so that you'd start gaining fat. Veggies in general have a low GI. I'd think it would be faster carbs (carbs with a higher GI) that would cause problems for "oversensitive" lowcarbers.

So I think it's fiber bloat. Try upping your water even more and move around as much as poss to help it go away. Have you maybe added some more salty foods lately? Those could account for the water retention. The headaches I don't know where to find the cause for. Any other new foods, spices etc you've added? Any other recent change in your lifestyle (added exercise w/o proper kcal intake etc.) Laxed with your water intake? Do you take any supplements?

Hope you feel better soon.

/gil