The key is too eliminate possible (could-be)s.
Half the symptoms you mention sound like low blood sugar.
Fyi - not all bloodsugar meters take the same reading as
doctor's blood sugar meter.
One of the meter series that do it right is one touch.
I use the ultra, but the fast take works fine too.
The strips are $$$, especially with no rx.
If no rx, you can usually buy them on ebay for $.45 each
compared to $.90 at the drug store.
Other issues could be cause too - but worth looking at
possibility of diabetes. If he's below 65, thats a concern.
If he's falling down and very sweaty - thats big indicator
he's 35-45 bloodsugar, which is insulin reaction.
100% orange juice works best (for me), instead of
food or sweets.
But low blood sugar could also be from hypoglysemia.
Some people eat a few too many carbs , then their insulin
over reacts 30-60 min later, and drops like a bowling ball.
The meter is about $65 and small bottle of strips $45.
Highly recommend he tries this for a while, to verify
or eliminate low bloodsugar from being the problem.
I am no dr buy has your dr, checked him for parkinsons disease, I worked with a gentleman who had parkinsons diease for a while and had low b/p for a while a nurse told me to get him to shake his hands and legs to help him to get his b/p up some and up and it seemed to help including his color o.J. Is good to. Also he could get another opinion from another dr, I am not recommending this stuff as I am not a dr but I do feel a second opinion or questions such as these to his dr would be good.
Seeing a neurologist , or a heart Dr. May help. I have also worked with diabetics.
He might be eating cake or something like a shot of booze while you are not there but to me that is his choice. He may be getting old and tired.
How old is your great uncle, not that age makes any difference, it could be his diabetes, it could be a lot of things. Does he have help? Feel free to pm me if you would like to.
My thoughts are with you both!
I do realize that this stated out as an olger post, I do hope things are better now!