You got your period. I gain 5 or more pounds each month like clockwork. Not much you can do about it, but stick with it and you should have a nice loss next week. It's normal for most woman to see a gain. Exercise can also cause muscles to retain water to help them heal. This can show as a temporary gain on the scale, no loss or smaller loss than normal. It could also be too much sodium the day before weigh-in or even if you had a high caloric day a day before weigh-in. So many factors that affect the scale.