I only had intercourse with my partner only. he got checked by a doctor a few days ago and doesn't have sti/stds. i have pale yellow chunky discharge?

Needs exam: The female genital tract is made of surfaces that create mucus that can support many simple germs. The location so near the anus also permits cross contamination from gut germs/yeast that lives in poop. This does not sound like a STD but female equipment occasionally requires maintenance checkups, especially when something like this develops.