Burning sensation left side of stomach along with bubbly feeling in same area. i'm currently 4 days late and nauseous i've taking test and they're neg?

Pregnancy is not the: Only reason for a late period. 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. #1 reason is pregnancy.