I am a relative newcomer to the vagaries of PD - coming up to my 3rd anniversary. I am only a couple of years younger than your OH. His symptoms sound very much like mine when they began. I first noticed that my right hand started to shake after a workout for about 2 minutes, stopped, and then came back a couple of months later for about 4 minutes. I never thought anything about it until the stress of an airplane flight from hell caused my hand to shake beyond my control for a few hours (you can read about it my August 12, 2011 entry in my blog "I've got that Parkie feeling" at www.wpgchap.blogspot.ca.) After that trip, I got concerned and went to the doctor.
So your OH and I have intermittent shaking in common.
We also have exhaustion in common. It has been described as exhaustion at a cellular level. I wake up tired.
Still, the fact that we have 2 things in common does not mean he has PD. A number of things can cause both symptoms. I can't remember a list of those things but my neurologist checked for them all in order to eliminate them as a cause. So get your OH to a doctor and my advice, get a diagnosis from a couple of doctors (I went to 3 neuros and, wouldn't you know it, they all agreed I have PD!)
So I have lived with PD for only 3 years and nobody can tell by looking me. My shaking hand is calmed by the drugs and I live a relatively normal life. I exercise every day (minimum 1/2 hour); my wife ensures that I have a healthy diet and I have a positive outlook for the future. I also continue to work but I am able to do so because my office is in my home and that afternoon nap sure comes in handy.