I think it’s Braxton Hicks

I’m only 16 weeks with my first. Today I’ve found myself having to catch my breath a few times cause of a sharp tightening right below my belly button. It’s happened about 3 times over the course of the day. The tightening only lasts for a couple seconds but I thought Braxton Hicks doesn’t begin until week 22. Is this Braxton Hicks or should I be worried? I’ve had a normal day. No heavy lifting or excessive exercise. Just household chores and walking my dogs. I hope nothing is wrong.