My cum smells different...help

So usually I eat the same diet and foods etc. my cum/vaginal fluids usually don’t have a smell, or if they do it’s usually very unnoticeable. For example after I masturbate sometimes I reach down there and smell it just to be sure everything’s doing okay.

This time it didn’t smell like normal...it wasn’t strong or pungent by any means, but more of a slightly bitter smell, the only thing I could compare it to would be the subtle smell of earwax.

The only thing I’ve changed in my diet is that I’ve started taking a Multi-B vitamin daily. Do you think this is the cause of the change in smell?

Or perhaps this is a one-off?

Also FYI, I haven’t had sex in like a year haha so it can’t be that.