What Causes Severe Headaches, Numbness And Tingling In Limbs?

My brother was taking bystolic for his blood pressure. Usually ran 145/80. He also has a low heart rate. Usually around 40-45. He had been taking this drug for several weeks and had very bad headaches and numbness and tingling in arms,fingers,legs and feet, also has had some in his face. He noticed the medicine stated not to take with low heart rate. He had already been taking it when he noticed it. He has been off of this medicine for about 5 wks but is still having same problems. When he lays down at night he is unable to sleep because arms and legs go numb. Could this still be a side effect from the medicine? He has had a ct scan, mri, nerve tests and all have been normal. Could this be caused from low heart rate or where should he go to be checked?