Recurring yeast infections for 6 months

For the past 6 months I have recurring yeast infections from hell. I’ve done OTC treatments as well as prescriptions and nothing has helped. It comes back within a week. My partner was also treated as he had a yeast infection at the start (back in July) and his has since cleared. I’ve done STI testing and everything is negative.

I’m at my wits end and considering taking out my copper IUD that I’ve had for 8 years as that’s the only thing I can think of that is harboring yeast and is apparently untreatable.

Has anyone else experienced this?