BH at 5 weeks?
Hmm... I had this with my last daughter's pregnancy starting at 7 weeks. I think our bodies become more intune to symptoms with each subsequent pregnancy. In the case of miscarriage, you would likely have painful cramping and blood with clots. If you are super nervous about it, you could call your healthcare provider for more insight, maybe bloodwork or u/s if you feel you need it.
Meanwhile, Staying super hydrated and avoiding heavy lifting when you can (easier said than done with a young child... I usually say something like, "let's walk to the couch together and I can hold you there." Or, if needing to lift child into a cart or something, I'll ask them to jump up to help me. "You need to get in the cart. Let's try to jump in! On the count of three... One, two, three... Jump!" and then lifting them up with that helps a lot.) will help decrease BH and probably make for a less worried momma!!
Definitely drink lots of water as someone suggested. Cramping doesn't always mean a m/c btw...I've had several and I've never actually had any cramping with them until *after* I start bleeding heavily. See if it resolves itself after a day or so. Of course if it gets worse or you do have bleeding (or if it would just make you feel better) you could contact your care provider.
Contractions occur throughout every pregnancy, as our bodies grow and stretch to accommodate a growing baby. It is very normal in most cases. I didn't notice any BH until the last few weeks with my first pregnancy, probably last few months in my second, and starting around 16-ish weeks with my third. I have noticed them constantly this time. My midwife who delivered my boys said she had such noticeable BH from 6 - 7 weeks with one of her babies she was sure she would lose it...and she carried to term. We become more used to how it feels, more aware of it, and our bodies stretch faster and easier after a few pregnancies. Unless you notice other worrying signs, I wouldn't be concerned.