tmi (mucus plug)

Sooo... the last like 10 weeks I have had mucus coming out which my doctor assured me grows back. I had her check to make sure I didn't have an infection, and she said nope and that everything looked great. Well now 32 weeks I wake up to this huge glob in my pad and had extreme lower back pain all day. It has gotten worse at certain times as well. I have had 3 other children but was on bed rest and induced with all of them. So I am not sure I ever lost a mucus plug and I never had back labor or went into natural labor. Is this normal ??