Mucus plug

Beverly • I'm 24 years old. Pregnant with my 2nd. I have a daughter who is 4. I kinda want another girl but will be happy no matter what. Fiancé is hoping for a boy.
So I'm pretty sure I lost some of my mucus plug cuz it looked like snot. But on call doctor says it would have old blood in it if it was my mucus plug. Is that true???