[MilnerRoute]

Stress will poke holes in your memory. (I once thought that taking statins might be affecting my memory - but stress was the more likely cause...)

I've also heard that exercise can boost your memory. (Possibly in part because it improves your sleep, but it also enhances oxygen flow.) Or maybe it just reduces your stress.

You've ruled out "anything pathological" - otherwise I would suggest mentioning it to your doctor. But I've always wondered if "brain plasticity" is what's causing us all to adapt to our new habit of endlessly scrolling Facebook/Hacker News/Reddit/Twitter -- by adjusting our perceptions to handle shorter bursts of attention. There've been articles and books written on the subject, but the fix they often recommend is just: unplugging for a while.