I wish I had some deep words of comfort and wisdom for you..........but I don't. All I can say is that my thoughts are with you as you struggle. I know that we codies have a tendency to make worrying an olympic sport. It's amazing the crazy stuff we find to worry about and the crazy paths our imaginations will take when we're worried.
Please don't think I'm saying there's no reason to worry. It's always concerning when someone drops out of sight..........especially when that someone is your loved one. All I'm saying is that the odds of it being the "worst" are a lot smaller than they seem in your mind right now.
Others will be along who may have some other thoughts/suggestions for you. As for now, please try to turn him over to his HP. I'm realistic, tonight will likely be a sleepless night for you. Keep reading and posting. We're here for you.