sidse, do you know which bacterium you have? Enterococcal infections of the bladder are quite common in menopausal women, and you need to have the correct AB for this, although Fosfomycin ought to do the trick according to the information on Wikipedia.
My last two UTIs were enterococcal, but so close together I'm not sure the first course of ABs really cleared it. I was given 7 days worth of Nitrofurantoin the first time, and 3 days worth the second time. I developed the infection just before Xmas and could not get treatment until the New Year, which perhaps was why it was difficult to shift. It did give me lower abdominal pain at first.
JP x