etzhadaat

I can't see your diary and I don't know your history. My "obvious" guess is that since you're dieting you're protein deficient right now. Eat some supplemental protein like a chicken breast or a protein shake and try again tomorrow. It might generally be a good idea to eat enough protein to reach your maintenance calories…

My daily goal is 1500 but I end up under 1200 pretty commonly.

It's pretty common that someone will talk about this on r/keto, it's probably potassium deficiency.