Try to wrack your brains and see if there is any possibly inciting cause, bin raiding? leftovers? any other signs associated? The vast majority of vomiting and diarrhoea cases I see resolve with symptomatic treatment with no specific cause being identified. I attribute most of the ones I see to having scavenged something, either different food or some other "sh1t" while out on a walk for example.
True, vomiting and diarrhoea can certainly be a sign of numerous other disease states so some diagnostics may well be warranted on the next occasion to rule out some basics.