Need ideas: confused emotional and gets obsessed

For issues specific to caring for someone with mental ill health.
Hi a friend and her family members thinks her husband has a condition that has not been diagnosed.

He appears to mis hear things (he has tinnitus in one ear) gets confused and can totally get the wrong end of the stick in a situation reading things into it that aren't going on and accusing people of saying things that they haven't. He then won't listen to anyone he has accused and has created big arguments.

He also gets obsessed about thing and can hear that it's good for people to drink water for example and then go on about it at every meal time to family members for a year, although he has different rules for himself.

He finds it hard to deal with others emotions if they are upset or angry and gets very upset himself in return making the situation worse.

He is reluctant to get a diagnosis, has anyone got any ideas please?

Thanks
How old is he please?
50 ish years old
This website has a good overview of mental health conditions, if you think that's what it may be
https://www.mind.org.uk/information-sup ... -problems/
Other than that could it be Brain damage from an injury or stroke or alcohol or substance abuse?
But you do need get a proper medical investigation to be sure. We are only amateurs
I would say a brain MRI scan would be an essential first step, to see if there is anything 'physical visible' going on inside his head, and at least to rule out that possible cause if it looks 'all clear'.

The other thing I would be at least 'potentially aware of' is the start of dementia. It's not always obvious that dementia is starting to 'set in' and it can affect people in very different ways. It can be hard to realise that yup, all this 'stuff' is being caused, at root, by dementia kicking off....

However, if it IS dementia, then it might be hard to firmly diagnose and also it raises the tricky question of whether he would want to know - it's a scary diagnosis after all.

I know it's very young to be thinking of dementia, but, grimly, it does sometimes have an early onset.

Hopefully, though, a brain scan might reveal an 'actual' cause that might then be treatable. Even 'non-brain' (ie, no obvious physical abnormality in the brain) forms of mental illness can be treatable (if treatment is accepted, of course....)

Do you think he's aware that he's behaving 'strangely'?