Why does it feel like I’ve done a full core workout?

[LaWI13]

So I found out I’m pregnant with my second last Wednesday (7/5/25) according to my app it says I’m 5weeks today and my stomach feels like I’ve done a full core workout! I have been sat in the car for the weekend (2 days of driving 5 hours each way) and I did a fair bit of walking yesterday but nothing core related! I’m worried as I don’t remember if I felt this way last time! Any ideas what it could be?
TIA x

I’m just over 4 weeks and feel the same, cramps really low down and if I’ve been sitting for a bit I have to get up slowly. Like I need to stretch my stomach out gradually. I had it with my last pregnancy but don’t remember it being this early.

I’ve not got cramping thankfully but it feels like if I sit for longer than 5 mins my stomach is a tight ball! It’s very strange! I don’t remember this from last time!