My fingernails are growing quickly and they are stronger (similar to when I am pregnant...but I am not) and I have put on 6 pounds in the last 3 weeks, even though I have increased my workouts from twice to 4x a week. Outside of Nov/Dec each year, I have always easily maintained my weight through a healthy diet and exercise, so this weight gain and inability to lose it through more exercise is not common. What could be causing this?