Moist/wet panty w/ little discharge sumtimes, low tummy cramps, late period, negative urine preg. test, lost of appetite, back pain. what is going on?

Infection: It would greatly depend on your sexual history. It may be anything from a urine infection to an STD. You should see your doctor and discuss everything with them.

Uncertain: Reasons for missed /late periods: low body weight, obesity, marked weight gain or loss, over-exercise such as in endurance athletes, breast-feeding, stress, illness, eating disorders (bulimia or anorexia), travel, hormone irregularities, drug use, medications (i.e., birth control) or med problem (polycystic ovary syndrome or Asherman’s syndrome. #1 reason for missed period is pregnancy.