I'm almost 25 weeks pregnant and I take our dogs for a walk probably 4 times a week. This past week or two every time I go, I start getting stabbing pains in my lower abdomen and then my stomach gets hard like Braxton hicks. This lasts for about the first 10-15 minutes before it stops and I feel fine the rest of the walk. It's so weird! Any idea what it is? I'm guessing it's just normal stretching but also kind of worried about it