Toprol-XL and dizziness and lightheadedness

Hi all! Glad to have found this site, I was starting to think I was going crazy. I am 36yr old female, started taking 12.5 mg toprol xl daily in March 2006. I had pvc's after working out in the gym and had a panic attack which sent me to the hospital twice in a week. The cardiologist prescribed the toprol and said it would help with both the panick attacks and pvc's. At first my side effects were mild chest pains, which have since gone away, but about 3 months ago, I stated experiencing dizziness and lightheadedness especially while driving or shopping, also instead of cold, I get hot easily and have had weight gain maybe 15 lbs. I have been unable to go back to the gym, I get very fatigued every time I even try to do any form of excercise. The panic attacks still come especially when I feel particularly bad from what I think are the side effects of this toprol. I am going to try to cut my dose to 12.5 mg every other day and see what happens, I will keep everyone posted.