If your intake of carbohydrate is very low, then your kidneys will dump both water and sodium. It's a known phenomenon -- see here:I have probably been in ketosis maybe 4 or 5 times since I started. So, is this my body adjusting to going Primal and flushing out all the bad stuff and will this finally go away?
The Blog of Michael R. Eades, M.D.Tips & tricks for starting (or restarting) low-carb Pt II » The Blog of Michael R. Eades, M.D.
Maybe that's what's going on -- or part of it. Why it burns I don't know. What did the doctor say?
As well as drinking more water, I'd watch those electrolytes (i.e. salt your food moderately -- and perhaps take a little magnesium (and possibly potassium), too ). Also, unless you've a specific reason to eat very low carb you could allow yourself a little more in that direction. Here are Mark's suggestions of the diffrent levels for different people with varying requirements:
How many carbs should I eat each day? | Mark's Daily Apple