Perhaps your medication is interacting with the alcohol? A 10 lbs. gain in 6 weeks sounds pretty high, especially if you haven't been eating thousands of extra calories. Maybe you have fluid retention? Sometimes you can become dehydrated and your body will hold on to every drop of fluid. Try drinking at least 8 glasses of water a day to prevent dehydration.
I find it's very helpful to keep a food log and write down everything I eat. Maybe you could try this without changing your diet just so you can get an idea of how many calories you are actually eating.
Stress will always make me gain weight. It's probably the way our bodies react in order to 'save' calories=fat for a percieved emergency.
I hope the weight comes off soon.