It's just discharge. As long as it is white and it doesn't smell funny, your fine.
"Vaginal discharge is normal and varies during your menstrual cycle. Before ovulation (the release of the egg), there is A LOT of mucous produced, up to 30X more than after ovulation. It is also more watery and elastic during that phase of your cycle. You may want to wear panty liners during that time.
The things to be worried about include if the discharge has a yellow or green color, is clumpy like cottage cheese, or has a bad odor. If worried, see a doctor.
White: Thick, white discharge is common at the beginning and end of your cycle. Normal white discharge is not accompanied by itching. If itching is present, thick white discharge can indicate a yeast infection.
Clear and stretchy: This is "fertile" mucous and means you are ovulating.
Clear and watery: This occurs at different times of your cycle and can be particularly heavy after exercising.
Yellow or Green: May indicate an infection, especially if thick or clumpy like cottage cheese or has a foul odor.
Brown: May happen right after periods, and is just "cleaning out" your vagina. Old blood looks brown.
Spotting Blood/Brown Discharge: This may occur when you are ovulating/mid-cycle. Sometimes early in pregnancy you may have spotting or a brownish discharge at the time your period would normally come. If you have spotting at the time of your normal period rather than your usual amount of flow, and you have had sex without using birth control, you should check a pregnancy test.