Ever since i've had sex last week i've had thin watery discharge ? what is this ? am i peeing on myself? why is the consistancy so different?

MAYBE AN STD: Since it is only about 1 wk, if pregnancy happens, it would not be causing such vaginal discharge. At this point, I am concerned for possible std such trichomonas which often cause frothy/watery discharge. Chlamydia can do so a bit as well, without much of other symptoms. I recommend getting it checked out. These are quite common, but treatable and preventable. Good luck.