recurrent bladder infections 13 years after bladder sling

The bladder sling surgery I had back in '94 allowed me to regain my life, my passions. I am so grateful for that ! However, I just recently, about 5-6 mos. ago, began having problems with recurring bladder infections. I took antibiotics once, but the four times since then I've tried Azo, a cranberry supplement. If I hit it hard enough I can return to what feels like normalcy. I did this a few times. However, the UTI's keep recurring with little break time in between. I believe I've been averaging 1/month. It seems that either I'm not completely getting rid of the bacteria, if these are indeed UTI's, or perhaps there is an issue with the sling itself that is causing me problems. It "feels" like there is pressure, almost like a hard budlge, indicating that the sling may have dropped. I don't know what happens to slings over time. I am trying to get some answers that may help me know which direction to go to figure this out. I am frustrated with the constant pain upon urination. I've had as many UTI's (perhaps) in the last 1/2 year as I've had all the rest of my life. 8-|