weighing oneself

Ok. So I am working on getting back into shape. So I wieghed myself 2 weeks ago and I was 188 lbs. Due to weather I haven't been able to get to the gym. I weighed myself this am after I got up and I was 170 and was confused and then weighed myself an hour ago and got 188. This may sound dumb but does anyone know why it could have changed so drastically in 12 hours. Or why i was less this am.