I think that either is possible here - you could have developed sensitivity to the nuvaring (which can, by itself, lead to vaginal irritation), or this could be a developing yeast infection. You don't mention any irregular discharge, or any visible redness/inflammation, or odor, which could help indicate an infection of some sort (either bacterial, yeast, etc.). But either is a possibility.
You should, at this point, call the physician who prescribed the nuvaring to you. They will probably need to see you to let you know if you will be able to continue to use the nuvaring. Since some people become sensitized to the product, they end up being unable to use it. If this was an infection, however, you could be treated and potentially continue with the ring. So give a call - they should be willing to see you.
I hope this helps. Please let me know if you have any further questions - I'm more than happy to help.
Take care - Dr. Fay
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