I too just make my own up with fresh lemon juice, sugar/honey (though you could substitute sweetener) and a good glug of whiskey!!! Its the only time I can stomach whiskey but it gives me a good nights sleep!
Whatever you choose, forget about the syns for a day or so, until you're over the worst of your symptoms. You need to get over the poorly bit to enable you to concentrate properly (IMHO).
Oh dear no good!! Don't succumb to the snack cupboard lol! I actually feel better munching on fruit with this cold now about to have my second lemsip of the day x