Hello, If your previous cycles were regular, then having unprotected sex 2 days before expected period date is very much safe. Here, chance of pregnancy is nil literally. But you should wait for next normal period. Reasons for irregular period with light flow are hormonal imbalance, irregular diet habit, mental upset, psychological factor, weight change, thyroid disturbance etc. You may need to undergo some investigation if you miss next period. Stomach cramp & gaseous abdomen are mostly due to indigestion problem or altered diet pattern. You can take some antacid to alleviate this problem. In this stage, you must take balanced diet with iron supplements, avoid stress, drink plenty water/ fluid, keep bowel habit regular, do physical exercise, eat carotene based vegetables and take sound sleep. Be well & always practice safe sex.