I’m still not sure if this is straight-up OCD; for it to simply manifest itself for No reason when I’m almost 30 just makes no sense to me.
This is a pretty new and still-controversial diagnosis, but have you asked about PANDAS? The “P” is for “pediatric” meaning for children, but it does describe the sudden onset of OCD where none was present before. Maybe there’s an adult equivalent? Again, fair warning, it’s a brand-spanking-new diagnosis and hasn’t even had enough time to differentiate itself from the pseudoscience-of-the-week (and it may well end up being a dead end upon further review), so you’re likely to get a raised eyebrow at the very least for even discussing this. Still, others have reported the sudden onset of OCD behaviors, regardless of the cause.
The downside of new diagnoses is that the therapies are even less proven, if they exist at all.