I like taking nap after I have my breakfast and whenever I dose off suddenly I will feel abit of stomach pain like needed to go toilet shit that kind of pain. I always got waken up by the pain and it last for 15 mins. Like everyday there will be one time of this kind of feeling and usually is when I am taking a nap. I was thinking is it contractions pain? Because I really don't know how contractions feels like.

You're probably experiencing false contractions. The real labour will be similar to that except that the interval is much much shorter. You may want to download a contraction calculator app to time your contractions. Usually your gynae will advise you to head down when you experience contractions every 5 minutes. how the app works is to see how long each contraction last and what's the time gap between each contraction.