Hi Prowife. I can think of something to try, before contacting your husband's doctor. Count your husband's pain medicine before the two of you go to bed. Count it again in the morning. Or, put the medicine in a secret place where he can't get to them during the night. If he objects, tell him lovingly that you are very concerned about his health and want to be sure he sticks around for a long, long time.
I had a medicine change several years ago that caused me to sleep walk for several months. It was the most unsettling thing to wake up the next morning and discover things that I'd done during the night. When I told my doctor that I was sleep walking, he simply said, Lot's of people sleep walk. Don't worry about it.
I locked up my medicines, then worried that I'd figured out how to get to them during the night. (I never did.) I DID almost sleep walk right out of the house one night. We have an alarm that needs to be turned off at a keypad before opening the door. There I was, punching in the code. Fortunately, the beeping of the keypad woke me up and I went back to bed.
Doing things in a sleeping stage can be a scarey thing to discover later on. If your husband IS taking medicine during the night, he might try to find the medicine if you have hidden it. He might not even be aware that he's doing it. But he might finally agree that it's time for a trip to the doctor for a medicine check. Good luck!