T.R.
Congrats on your loss so far!! The temporary weight gain can be due to a number of different factors.
First of all, unless you consumed an additional 25,000 calories above & beyond what you normally eat in the last 5 days (cheesecake binge, anyone?) it is not possible that the 7pound weight gain is "real".
Instead, it is likely a fluctuation in your bodies natural retention of fluids.
We can retain fluids, or "water weight" for a number of different reasons. If you have a propensity towards swollen feet/ankles & hands (called edema) it is not unusual for your weight to vary by 5+ pounds day by day. I have this issue, & take a water pill to keep it under control.
Hormonal shifts can also cause this, so when you are a week out from getting your period, your body can have a tendency to hold fluid, giving us the bloated feeling.
Sometimes what you eat will also cause a water retention, when you consume overly salty foods, such as chips, lots of processed foods, pizza (there is a lot of salt in the cheese!), chinese food is notorious. Bodies like to stay in equilibrium, and so if you bring in salty foods, the body grabs the salt to bring the cells to the same concentration as the passages the food are travelling in. Then, when you have finished eating, your body holds onto water to help equalize the cells that became extra "salty".
Since you've been working out, it is possible that your body is reacting to the changes you are putting it through physically. Muscles need to have water in order to perform the biochemical processes that give us energy, so when you begin working out, or change your workout routine, they may grab onto water to stay prepared for the activity they aren't used to yet. And this can take a while before your body settles into your "new" rhythm.
It is recommended to drink plenty of water when you are working out, so that your body has it available at all times, & will be less inclined to store it for the future. Each person is different in their needs, but to replenish what you lose in exhalation, sweat, normal daily activities, etc. usually requires about 48-64 oz, more so if you are going to work out, or drink caffeine.
Now, if you are having swelling in your hands/ankles/feet, & this is new, you should see a doctor to make sure it isn't a symptom of something more serious. But if not, hopefully one of the reasons above is the cause of your scales demoninc response this morning, & if that's the case, know that it's only temporary.
Keep on doing what you're doing (unless its eating salty foods, then cut back *smile*), and good luck on your future healthy weight! T. =-)