pH imbalance !

Hey guys so recently I started the Nuvaring and my man has been cumming inside me. Sometimes I feel an itchy or burning feeling after sex. I don’t have any infections or anything all the tests came back with a “normal flora” but I don’t know how to fix this.. can his cum be causing the imbalance? Or does it sound more like a side effect of the ring? How can I get rid of this? Any advice is appreciated thanks!