Is this weight gain from my period?

Hey so I’ve been back on keto for a week now and I’ve been losing weight at a very fast rate. I recently just stepped on the scale this morning and it looks like I gained some weight (about 2-4 pounds). I’ve been on my period for 3 days now and I don’t know what could have caused it. I’ve been within my macros and have done everything properly so I know it isn’t me. I don’t use artificial sweeteners either or gave in to any of my cravings. Help please.