have you lost your mucus plug?

With my first boy, I saw my mucus plug at 36w and a few days and a week later, my son was born at 37w 3D. I am 29w 1d with baby #2. I saw a thickish yellow (snot like) discharge when I went to the bathroom. I never had this with my first son. Is this just discharge or part of my mucus plug? It concerns me because my son came within a week after I lost it. I'm so confused to what I just saw. Does anyone know if it is just discharge or the mucus plug? I have an appointment in two days, so I will mention it to my dr.