was I spiked????

Staying at a friends brothers house (with housemates) me and my girlfriends had a night out in Manchester. I only had a few vodka and cokes and usually can drink twice as much as I did but this time I couldn't walk and have no recollection of the night at all... I remember the first few drinks but nothing until I woke up the next morning. To piece bits of the night together I asked my friends what happened and they said I was out for half an hour and couldn't function whatsoever, I didn't talk a lot and they took me back to the flat after half an hour of being out, I hadn't drunk anymore. Soo from 12 midnight to 3am I was on my own (from what I can work out) and when my friends returned at 3 they said I was wide awake and really chatty. Then at 5 we all went to bed, I still to this day, have no memory of the whole night.