Contraction that won't go away??

39+3 here, and all of a sudden my belly went rock hard and has stayed that way for nearly a half hour now!!! Baby is moving within my hard belly - kicking around, so I'm positive it's not just the baby pushing against me ... But I've never felt this before. I've had BH, but they tend to go away. This is a feeling like my belly skin is so swollen/bloated that I'm going to literally pop! 😧 if this doesn't go away I'm going to call the dr tonight to make sure this is normal - it's a super weird feeling ... Anyone else experience this?