What you're experiencing really is perfectly normal. It's nothing more than a temporary water weight gain that passes in a few days. You may have noticed you "gain" weight during your menstrual cycle. This is not unusual. Many women tend to gain weight. Is this a fat gain ? Nope, it's nothing more than a temporary water weight gain that passes in a few days.
I can easily gain or lose as much as 3-4 pounds in a day because of a shift in my water weight. Try not to fixate on the scale. Remember, there is more to good health than a number that stares at us from between our toes in the morning.
You're doing just fine.