15 weeks and loosing bits of my mucus plug?

This week i have lost bits of my mucus plug twice. I have been pregnant before and its exactly the same stuff as what i lost with my first although i didnt loose tht til 34 weeks. Its yellow almost green very thick blobs of what looks like snot. I have called my dr 6 hrs ago but he didnt call back. I dont have any pain at all. Im scared my cervix is starting to efface or dialate and that im gonna end up miss carrying. Has anyone experience this in early pregnancy? Should i go to the ER evn though im not in pain?