Pieces of mucus plug at 15wks!!

Ca

Okay so today I'm 15+2 and my belly has been tight and sore allllll day. Well I just went pee and happened to look in the toilet before flushing and I'm almost positive there was some of my mucus plug in there!! I'm a FTM so I have no idea if this is normal or not. I can't call my doctor cause they're closed for the night.

Is it normal?

Should I worry?

Does it grow back??

And the tightness, is that BH?

Sorry for all the questions.. I'm a worry wart and I'd rather get answers from other mommas than go to google and freak out even more!