Watery light brown discharge

Going to make an appointment with dr soon. Just wondering if anyone on here might have any ideas for what could cause this kind of discharge? Has been going on for a few days. It’s the consistency of water and kind of pale brown and white.

Have taken multiple pregnancy tests, all negative, and haven’t had period in a couple months due to I think stress. Tender nipples too but no other indications of period. Anyone got any ideas?