possible depression, 83 yr old father

[poppym12]

I'm very worried about my dad. He has various health issues but has coped admirably well. Just over 12 months ago he was hospitalised for breathing difficulties. He has lived with heart failure for over 20 years and has copd. SInce his hospital stay where he was treated for pneumonia, he has become fixated on his medication box, daily counting his pills and reading through the leaflets and talking about how ill he is - I totally understand this anxiety
I see my parents a couple of times each week, take them shopping and out to lunch and visit most saturdays. They've even had a couple of short uk holidays which he enjoys, they both do. Today he has just sat staring into space, not wanting to talk to anyone. My mum says he's like this a lot,he puts the TV on but stares in front of him at nothing. If she asks what he's doing he says 'pondering' or that he's depressed. However, he will not talk to anyone about this.

I don't know what I'm asking, I'm sorry. I'm just so worried about my parents. My mum's health has declined recently too and I dont know how to help them. Any ideas where I can search for advice please?