My period is about 2weeks late, i have soft cramping and a strange watery light briwn liquid leaking out. pregnancy test was negative, what's going ?

Not sure.: Reasons for missed/late periods: low body weight, obesity, marked weight ^ or v, over-exercise, endurance athletics, breast-feeding, ^ stress, illness, eating disorders (bulimia or anorexia), anovulatory cycle (no egg released), travel, hormone irregularities, drug use, meds (i.e., birth control) or medical problems (i.e. PCOS). #1 reason is pregnancy.

See your doctor: It is possible that a urine pregnancy test was false. A blood test would be best and your discharge should be evaluated.