Early labor?

Ma

So I had my son early in 2016 at 34 weeks. Today I am 29 weeks with a baby girl and I've been a bit stressed. I've been having contractions on and off for the last few weeks (since 22 weeks) just now my entire mucus plug fell out and it has a stench to it. Is that a sign of early labor? Should I go and get checked out? Or is that not a sign? I do know it can fix its self but will it when the whole thing falls out?