I have been suffering from monthly water infection type symptoms which ocurr about a week before a period.  I have taken water samples to the doctors which have all been clear. I have had a kidney scan and a sample taken from my uretha.  I have tried extra water around this time aswell as cranberry jice and cranberry tablets.
HI, thanks for using Chat Doctor If no bacteria is detected in the urine then it is possible that the cystitis may not be due to infection. Cystitis is inflammation of the bladder and there are different types/causes. One type is interstitial cystitis, this is the possible cause of your symptoms. You may want to consider consulting a urologist to see if this is a possible diagnosis for you so that treatment can be started. I hope this helps