Sleeping too much?

Hello. I am new here and decided to post something because I am slightly worried. My husband has been sleeping a lot lately and I am wondering if it can be bad or not.

Since about a week ago, he has been sleeping for 15+ hours a day and he would still feel (or at least, look) tired after. He doesn't do much yet he is always weak, as if he has been doing a lot of physical work and he had lost his appetite. The only thing he is willing to eat and drink in large quantities is milk.

Just so you have an idea of how he is, I should say that he has a few mental issues. Nothing big, but he had lost the ability to speak and do various task that are fairly easy to the average man. He also became slightly immature and acts like a real baby sometimes. After what I rather call an accident, we don't have a husband-husband (yes, we are gay) relationship any more. Now, I am more of a provider/care-giver than anything else. After his brain got damaged, he pretty much forgot everything and I hope one day his memory will come back …

The thing is with his excessive sleeping, I don't go to work and I am so close from losing my job. I need this job to pay for everything he needs, but I don't want to leave him alone or with someone else while I am away. I am very paranoid and I trust very few people.

So, what can it be? Before scheduling with a professional, I'd rather see what other people think. Anyway, hubby is not too fond of doctors.

P.S.: He is young (26) in case that makes a difference.
P.P.S.: Today, he has been sleeping for a grand total of 14 hours ... and counting!