I had this happen to me a few years ago! It was so bizarre and it did seem to correlate to eating protein and I had never even done any form of fasting back then.
That being said, I went to the doctor’s, got a kidney test, they checked for infection, checked the cloudiness of my urine incase I had a fistula (basically a hole somewhere inside that allowed air to bubble through) but it was all clear.
At the end of the day it cleared up with no apparent cause but I would definitely get checked out as it could be serious of kidney related.