Welcome to HCM
Read your prob, why are you take it for preventing UTI, it cant be used prophylactically.
if you have any infection then it works other wise it has side effect also one of them is gastritis
which you have. so dont take it without any sign of infection it is harmful for health. after taking any drug for long period it cant work further as its resistance developed so if you will have UTI again you should take another tab as per advise of your doc. so stop both of tab .if you feel you have UTI science past one yr then you should get complete urine analysis n urine culture then after consulting your doc.