I think the cranbery cocktails are definitley to sweet.
Another way is to buy a bag of fresh cranberries, put in a pot, add the whole bag of cranberries fill with water to cover berries, bring to a boil, then simmer until all the berries have basically broken up and floated to the top. Discard berries if you want and drink the juice, do not add sugar, this is much better if you have a bladder infection or you just want to drink a healthier cranberry juice.
Also you can get a good bottle of cranberry capsules with vit.c in them.
You can take this at least until your are feeling better.