Just to let you know : don't drink the cranberry!!!
Cranberry is great for preventing infections, as it coats your urinary tract and stops bugs 'sticking'.
But when you have an infection, it also coats your urinary tract and so stops the antibiotics from working properly.
Lots of water, diluting juice, avoid tea and coffee and other caffiene type drinks.
Keep an eye on your temp, and the quantity of urine you are producing. If your pee gets really smelly or you can't pass any or it seems to be pinky or very dark, get back in touch with the doc. It is possible to show up nothing on the stick if the infection is just starting to develop.
(Veteran of at least 50 infections, stones, all the tests etc ....)
Hope you feel better soon. Sorry, I know nothing about the antibiotics, I almost always get Ciprofloxacin, but I just googled it and it is used as an alternative antibiotics in people who are allergic - like you!