Had to take my little terrier to the vet today.

I noticed her leg looked misshapen around her knee and when she put her paw down to the ground her leg shook.
I checked it and found her dew claw had curled and cut into her leg. I called the vet straight away and got her in within the hour. The vet trimmed it and removed it within seconds. She's got some antibiotics but is back to her old self....thank goodness!

But how guilty do I feel? I should have noticed when I clipped her out a couple of weeks ago.
She's 13 years old and never been any trouble.....I just feel like I've let her down letting it get so long and painful without noticing.

I had the same thing happen with my older cat, one of her regular claws grew around and into the pad of her foot.  I don't normally trim my cats' claws, they've kept them short on scratching posts.  But I guess as she aged she didn't do that as much and one went wonky and grew more than the others. Because it was only one, the others were fine.  Possibly the same thing with your pup?  And I bet she has curly hair so a bit of camouflage.  I felt horrible too but your Vet knows you are a good pet parent and it was just a weird thing you didn't catch.  Alls well that ends well.

Same thing here last week with a 14 year old cat! I'd not noticed a thing.