so I have heard that your mucus plug grows back but this is my third pregnancy and I've never had it…

so I have heard that your mucus plug grows back but this is my third pregnancy and I've never had it happen until this one....why does it happen? could it be from me doing alot?? I walked around a ton today and a picked up some things I shouldn't have like my daughter cause I'm having trouble with feeling pain in my vag. and I got in a fight with the hubby today :( so I wonder if it is all because of everything or if it just happens