We just got back from a week in Portugal and I feel terrible. 
I normally eat as I like there (was practically brought up in Portugal and it all feels like Soul Food to me!) and I was reasonably careful this time - no unpasturised cheese (I had sheeps cheese but it was pasturised, which is fine), no clams (sob) apart from about 8 very well-cooked ones in a pork dish (all open, all tasted fine), no pate apart from a bit from a little vacuum-packed tin with some bread (which I've seen from several different sources is fine). I had ice cream, salad and egg custard tarts, all of which, I suppose, pose theoretical risks.
I had slightly loose bowels from about halfway through our week there but otherwise was ok, and felt a bit 'looser' yesterday on the way home. Today, I have diarrhoea, but not horribly, and almost constant nausea but not been sick yet. And I feel woozy and a bit dizzy. No temp, no headache. Sofa-dwelling and eating dry crispbread, plain rice and grated apple, basically!
Do I need to worry? I'm pretty sure the small amount of sardine pate I had would be ok, as it was tinned. If I ate a dodgy clam, that was 4 days ago now and they usually make themselves felt sooner! And they were all cooked, open and tasted fine. I'm just wibbling a bit, having been, I suppose, a bit less than conservative with the usual proscriptive guidelines and worried about Listeriosis, though I know it's very rare. It's probably just a tummy bug, isn't it?