What Are The Side Effects Of Metoprolol?

Hello, My husband had pneumonia and while testing him, doctors discovered that his aorta was 4cm. They are concerned about the size but he has never had an electrocardiogram before so they don't know if this is normal for him. He has been put on 25MG of metoprolol succ er once a day and has lots of muscle aches and belches severely at times. Could those things be a reaction to the meds?