Hello. 4 days ago I had something that looked like a plug, mucous and …

Hello. 4 days ago I had something that looked like a plug, mucous and transparent. There was a little yellow discharge. Today in the morning my belly hurts and my lower back. In the evening the pain increased. Before that, I had daily training contractions. But now there is nothing down there, without discharge. And yet my belly hurts more. Can childbirth start without bloody or brown discharge?