Atacand and Weight Gain

I have just started taking Atacand for my migraine prevention as before I was on Topamax.  The Topamax was great for controlling my weight and also helped a little for my migraines.  But, I was extremely tired and had no libido from it.  So, I decided to get off of it.  I have now gained a lot of weight since getting off the Topamax and I'm not sure if it's just my body reacting from that or if it's from the Atacand.  I've gained about 10lbs in 1month.  It's very disturbing and upsetting to me.  I'm only 5'2'' so even a little bit of weight is visible on me.  I eat well and I'm a vegetarian.  I work out 3 days a week but have tried to do more now.  Has anyone had a problem like this?