Could it be braxton hicks? Practice contractions?
They should cause no pain. Your belly becomes hard, like a barrel for a few seconds & then release again.
They are quite normal & happen in every woman. Some feel them, some don't. If thats what it is there is no need to think labour is close. They often start as early as 20ish weeks

Not everyone will have mucus or waters as warning before labour. Every body & every labour is different I never got the runs either.