Ideally, the
ring should be removed for the
hefsek taharah, one
bedikah each on
days one and seven, and for
immersion. You can leave the ring out for the
moch dachuk, which should make insertion more comfortable. Removing the ring for less than three hours should not reduce its effectiveness.
Findings on a NuvaRing are treated like those on a
bedikah cloth, so they can indeed invalidate a
hefsek taharah performed beforehand, depending on their hue. That would seem to be what happened in your case (unless there was more of a question about the hue and poor lighting). We suggest you bring the pinkish
bedikah to a rav for
evaluation, since it may retroactively be considered a new
hefsek taharah. Be sure to mention what you found on the ring for context.