It's probably dangerous to take linear trends in exchange rates too seriously, but NJ is basically right -- although the Brexit decision certainly accelerated matters. It's also possible that the pound's falls in the build-up to the referendum were influenced somewhat by fears that the UK might vote to leave. At any rate, the last three months have seen the pound bouncing up and down roughly around the same range; but it's pretty misleading to post that the pound "rises and falls every day" as if a 15-cent drop in about three hours is somehow normal.
But anyway. In the "interBrexit" period it seems that the markets are unstable, but in both directions. Despite the fears I had earlier that the pound would continue to fall, it's only occasionally threatened to do so, and is now bouncing around between about $1.28 and $1.34. Since that does represent a ~15% drop on levels pre-referendum, it's not too surprising that prices based on imports will either increase, or the amount you get for your pound will decrease, but hopefully this will be as bad as it gets.