It is possible that your drinks may have been spiked, but in my opinion, it is most likely due to food-poisoning
from something you had with your drinks. Had your drinks been spiked with visine, you would have been likely to develop blurred vision
and palpitations as well. Also diarrhoea
after visine ingestion is not that common. Since your main symptoms were vomiting and diarrhoea, the most likely cause in my opinion is a bout of gastro-enteritis
resulting from something you ate.