So apologies for graphic pic. But most months since MMC (6 months) I've been getting mid cycle discharge like this. Ie fairly bright yellow. Lasts a few days seems concurrent with EWCM. I've also been getting 2 days spotting just before the EWCM phase.
I'd be amazed if its an STI (only dtd with dh since more than 15 yrs) but maybe thrush/bv? No smell or other symptoms though. Just slightly alarmed by the colour......