If you have kidney disease before starting LCing, the WOE can aggravate certain conditions (I'd have to look them up to get more info). Kidney disease can stay pretty silent/asymptomatic, from what I've read, so it'd be a good idea to go to a doctor soon, imo. I hope it's nothing serious, but it's always better to be safe than sorry. And if it's nothing to do with kidneys, you'll have baseline kidney tests so that you can prove to yourself that LCing does healthy kidneys no harm.

good luck!