Diarrhoea at 19 weeks??

[BabyT20]

Just wondering if anyone's experienced sudden diarrhoea around 19 weeks?
I've been fairly constipated for the majority of this pregnancy so far but tonight, I was out for a walk and as I was nearing home, I had the sudden urge to go to the toilet. I just made it home in time and have had a couple of quite painful episodes of diarrhoea since.
Could this have been triggered by the exercise? Or does anyone have any other ideas?
I went into premature labour with my last pregnancy at 18 weeks so I'm petrified in case this is a warning sign for labour. I have a scan with my consultant tomorrow but just wanted to see if anyone else has any experience of this.

Yes I unfortunately see-saw between either constipation or mild diarrhoea. I’m 20 weeks and its my second pregnancy, this is normal for me X

I go between constipation and diarrhea. That's why I'm awake now

Morning, I am recently pregnant and this is all new to me i have done a self referral for midwive to contact me what else do I have to do. I feel like i am on my own.