Concerning behavioural change

My wife and I are very concerned and upset. We have a 7 year old cockatiel Dusky who we have had all his life. He is currently going through a big molt which started a little over a week ago so has obviously been a bit distressed and cranky as he always is during a big molt.

The last couple of days though his behaviour has completely changed to the point where he behaves like he doesn't know us at all. When ever we're at home we have him out of the cage, but after uncovering him today and yesterday he looks scared and when finally coming out of the cage flys around but behaves as if it's a foreign room. He even slept on a different perch last night which he never does.

He will sway and hiss at us as if he has never seen us before - it's like he's a completely different bird and this has never happened before.

Physically he appears fine - he is eating, his poo's are normal, he's flying around (albiet because he looks scared) and he's not sleeping more than normal.

Has anyone experienced this before? We have a local avian vet which we use, but the tiel hates being handled and a trip to the vet always completely distresses him so we avoid it if we can (especially when he's molting as he's already in a distressed state). In saying that, we will obviously take him if we need to but again, he appears physically fine.

Should we just ride this out and hope his behaviour returns to normal?

We would appreciate any advice.

Thanks.