Hello from JustAnswer.
There are a couple of concerns in this situation.
Yes, a UTI would be a concern. It is true that Cipro is one of the antibiotics that can be used for a UTI and is quite good for that indication. However, there is no antibiotic that works 100% of the time, and it is possible that a germ that is resistant to the Cipro is able to grow while taking the Cipro. Ultimately, proof of an infection caused by a germ that is resistant to Cipro would require a culture of the urine.
Cipro can affect kidney function, but this would usually present with a decrease in urine output, rather than increased frequency of urination. So, there is less concern about kidney failure with these symptoms.
It is also common for antibiotics, including Cipro, to cause diarrhea. The most common reason for diarrhea is that the antibiotic kills many of the good germs in the gut. In this situation, taking a probiotic can help to replenish the good germs in the gut easing the diarrhea. However, it is also possible that there can be a growth of a germ causing an infection, and the growth is aided by the loss of the normal good germs in the gut. While there are several germs that can do this, the most worrisome would be C. difficile. C. difficilt is more worrisome because it can cause a more serious infection and because there are few antibiotics that are effective against the germ. There are tests that can be done on the stool to detect C. difficile or any other secondary infection.
Of these interventions, the only intervention that can be done without seeing his doctor would be the use of a probiotic, so this would be the appropriate next step. It also is important to be drinking plenty of clear liquids to assure adequate hydration. If the symptoms improve with probiotics, then that would be an indication that the problem was due to the loss of the good germs in the gut, and as long as symptoms improve, there is no need for further evaluation. But if the symptoms do not improve quickly, then it would be appropriate for him to be seen.
If I can provide any clarification, please let me know.