Part of mucus plug came out and starting to dilate at 22 weeks? HELP?!

So I just went to the bathroom and I think part of my mucus plug has come out, it wasn’t very much and it has happened earlier in this pregnancy (midwife said nothing to worry about) but now I checked my cervix and I think I’m 1-2 Cm dilated!

I’m 22 weeks and a FTM, I a little worried that something is up because I fell over yesterday (nothing massive, just a little trip). When I’ve been doing stuff today, I’ve had some stomach and back aches too.

Any advice? Has anyone else started to dilate this early?