Its just a really bad pressure in the bottom. Its just so sore that there is really no mistaking it, trust me. I had a few contractions on waking up as i was overdue. On the actual day i went into labour in the morning, i had a few..but they were really spaced out..like 2hrs apart. By the time 6pm came, they were getting stronger...by the time 8pm came..there was absolutely NO mistaking i was in labour. The pains were so sore, they took my breath away and they were timing perfectly. I think thats the difference...the time between each is perfect and everytime it went
down a few minutes...the contractions were spaced the same..until they went down a few minutes again, until i was having one every 5 minutes and i was told to go in to hospital. I really wouldnt worry. I know its a cliche but you will know when you are in labour. I have never pooed in labour...or not that i know of but believe me, it takes everything out of you and you will not care. Your body just takes over.