The AF characterized by irregular heart beat is most commonly found in patients the previous High blood pressures or hypertensive heart disease. This condition is treated by converting the heart beat which is irregular to regular rhythm with help of drugs or DC cardioversion once it is established that there is no clot in the heart.
The bisoprolol can be used to prevent redevelopment of AF or (in case where it is not possible to convert heart rhythm to normal) to control the heart rate. IF the heart rhythm is nor normalized and remains irregular for long, one develops the risk of formation of blood clot in the heart which can spread to different body parts if not treated.
So Coming back to your question, the symptoms of achey, exhausted and breathlessness though are not highly likely side effects of bisoprolol but exhaustion and breathlessness can occur like mentioned above in those who develop broncho-constriction. Exhaustion can also occur if the bisoprolol causes heart rate to decrease more than desired or causes low blood pressures.
In addition, other diagnosis like pulmonary embolism (travelling of heart clot to lungs) can also produce breathlessness and exhaustion, other symptoms in such situation could be chest pain, hemoptysis (coughing up of blood). this is a serious condition and requires management in emergency room.
Furthermore, Achey, exhaustion and breathlessness can also be symptoms of lower respiratory tract infection, anemia, low cardiac output states..
So i would advice to consult your physician to report these symptoms for evaluation of the cause and proper diagnosis.
Feel free to ask more questions,