Pain at 19 weeks with twins

So everytime I stand, walk around, or adjust my position on the couch/bed I get pain under my belly. Almost like cramping, and an almost burning and my back kills me. I refuse to Google anything due to over worrying about what could be wrong. My question is has any women experienced this with twins or a singleton and all has been well? I feel the babies move all the time, I'm just worried about pre term labor or something. Also when I put my arm over the top of my belly I get pressure pain in my lower belly(learn more on Glow: