I don't think I've welcomed you before, so welcome to HW!
In my opinion, it does not sound like depression to me at all. I would get him in to see a neurologist ASAP. Get a neuro exam to make sure nothing serious is wrong in that field. Then maybe have some blood work run. Sometimes hormonal imbalances can cause depression-like symptoms, fatigue, insomnia/somnolence, changes in appetite, changes in weight, etc. Also, certain illnesses can cause problems like that. A friend of mine caught some sort of tropical illness on a missions trip to Venezuela some years back. The symptoms didn't get really bad until 3-4 months after he returned (I think he said they combined with some other illness -- it was a long time ago, I don't really remember perfectly). He got a lot of different problems. Lastly, though I would probably try to address this first, if he is on any medications at all or over-the-counter pills, call the prescribing doctor or primary care doctor to see whether it's possible that any of the meds, or a combination of the meds could cause his symptoms.
If all of those come back okay, you might try taking him to either a neuropsychiatrist or a psychiatrist for a thorough evaluation & treatment plan.
Gosh, I sure hope you find out what's going on very soon. Please do let the doctors know that he is having such unsettling symptoms when you call to make the appointment so hopefully they can get him in sooner rather than later. Let us know how things go or if there is any way we can support you during what I imagine is a very stressful time for you as well. I am always amazed at all the caring spouses here on this forum. You really are to be commended.
Moderator -- Depression Forum