What Causes Bad Breath, Muscle Jerk, Memory Problems And Weight Loss?

My husband has rotten egg breath and he is very out of it. His muscles jerk when he sleeps. He is 54 and has been on various meds for spinal degenerative disease. He is having memory problems and fells like he is loosing it. He is 6.2 and wt. is 178. He has been loosing wt. and he does smoke.