From 29 weeks now 30 - braxton hicks and more?

Other than braxton hicks i occasionally feel the base of my spine squeezing itself.. is that normal? I had it once when i was lying on my bed 2 days ago and then today when i was on the bus otw to work. #firsttimemom i tried googling it the other day but only thing i could find was back pain, lol this pretty extreme back pain i think