Hiya. You might have put some of the weight on b/c of 3 things that I know of without eating any different to the norm.
1 b/c of your change in meds.
2, If you don't sleep well, that can make you have a wight increase. (I just found this 1 out)
3 It is winter time and our bodies tend to store what we eat in the way of fat. Just like a squirrel would store nuts for the winter, our bodies do the same in winter. The body knows as we are less active in the winter, we eat winterly foods and the daylight hrs are much less. We are just like very other animal and our bodies know it winter time.
If you have been eating a little more sugary, fatty foods then the body has even more it can store for the winter.
There could well be other reasons as well. If you are really worried about it, then I would see your GP.
As for a quick fix. There are loads, but if you want to keep the weight off, there is not really a quick fix.
I have put a little bit to much weight on as well