There's actually a scientific reason why you might find yourself running to the bathroom a lot right before a big drop on the scale. I picked up this tidbit from a weight loss researcher who runs a lab that monitors people's intake and output.
Your fat cells store fat in a liquid form - it looks a lot like Crisco oil (yuck!) When you create a sufficient calorie deficit so that your body turns to its stored fat for energy, the fat empties out of the cell. BUT ... sometimes the empty fat cells will temporarily fill up with water. The result is that you've lost fat but you can't tell on your scales because you've gained water weight. Then eventually your body will release the water - whoosh! - and the weight loss shows up on the scales. You haven't lose two pounds of FAT overnight, of course - it's two pounds of water.
He says this is often what happens when people think that they've 'plateaued'. They've actually continued to lose fat, but their bodies are holding on to temporary water in the empty fat cells and so their weight isn't changing. If you're patient, eventually you will see the scales reflect the reality of your fat loss.
So don't be discouraged if you're working hard but nothing's changing on the scales! Tell yourself that you're still losing fat and just holding onto some temporary water in those now-empty fat cells. Be patient and don't ever give up!!