Stains in underwear, don't know what it's coming from!

[ProbablyStressing]

I'm a female who's 18 years old, and recently I've been noticing that often I get stains in my underwear. The stain kind of looks like a tea stain, I'm confident it hasn't come from discharge or anything because any discharge I have had has been completely normal looking. I don't get any blood when I wipe or anything, I'm hygenic, I'm really baffled what's causing these stains, it's like it's being bleached a different colour! I'm on birth control pills (have been for about 2 years now) if that could have anything to do with it?
I'm starting to worry as I just don't know what's causing it! :weep:

[Tommo1980]

Have you had a sniff? As a guy my guess would be a few drops of urine. Quite normal, even after a good shake/wipe.

Tommo x

[Emc]

Vaginal discharge can often bleach dark coloured underwear.

[Leslie735]

Normal. I have them too. Its from discharge that leaves behind stains.