Help?!

So I'm 38 + 1 and think I might be in early labour? I've been up since 3.45 this morning with what I thought was a trapped wind/ upset tummy pain but ever since my back is in agony and my stomach is extremely hard and uncomfortable. I think I might be getting contractions but they are about half an hour apart if they even are contractions. They feel like a wave of pain through my tummy and back. The only place I can get comfortable is in the bath or sat on the toilet lid. Anyone think this could be it?