Just got off of Rx steroids and need to lose the weight I gained from them!?

You've gotta love irony. I joined a gym to lose weight. I I was getting very very dizzy during my workout and discovered I have an inner ear problem. I went to the doctor for it and got put on Prednisone, a steroid, for 5 days. Because of the steroid I gained 8 lbs in 5 days! I'm only 5'1! I didn't work out during that time (b/c of the dizziness) and did have more of an appetite...I just don't think I ate my way to 8 lbs heavier! Do you think I'm just retaining water from the drug and I can lose it easily or does prednisone cause you to store more fat? I'm in a wedding in 10 days and my dress is tight now!