Toprol and edema

After taking Toprol XL for the past four years, w/o any side effects, I took the generic form of Toprol for one week, and began experiencing edema in my right foot. The swelling has spread to my right leg. There is some amount of pain in the both the foot and leg. I asked my doctor to phone in a short supply of brand name Toprol XL. I began taking that, 50mgs/day, yesterday. The swelling has not diminished. Has anyone else experienced edema related to this drug?