Toprol-XL and bananas

I have been taking Toprol for 2 1/2 years following bypass surgery. Some weakness has occurred, but I have bicycled 5,500 miles and even finished in the top five in a couple of amateur races during that time. I often have leg cramps, but have noticed taking a potassium supplement (or eating more bananas) and drinking more water seems to alleviate that problem. Other side effects include reduced sex drive and a need for more sleep and rest. When I don't get enough rest, I get so tired I can barely function. I am also taking Crestor and Avapro (the combination of which has caused even more side effects -- weakness, BP drops, dizziness, sharp muscle pains, sleeplessness, etc.)