Thanks, Swimpy, Noddy & J_B.
Thank you for your concern & suggestions.
I actually had my best night's sleep in a while, so am feeling a bit more perky. As I've been stuck in what feels like a cotton-wool cocoon for the past few days I've decided I need to move! So I'm going to put on my runners & get some (gentle) walking in. I hope that helps my back, it'll certainly help my head!
I need to check that there's still life out there!
Thanks again, everyone. Much appreciated. And welcome to A2K, J_B!