Pain on the left side

Agata • Little princess Kaya 🎀👶🏽🎀 due 4th of May 2016 💖 #cantwaittoseeyou
I've got a pain on my left side like on my waist when I'm lying down with every breath I take is very painful like some needles,but when I walk is fine I don't feel pain. I'm 12 weeks now and I have a sciatica pain on my left hip,does it have anything to do with that? Anyone else having the same pain? Please help