Lower abdomen is hard and tight

Is this normal at 17 weeks? My lower abdomen is very tight today and is hard. It's not painful, just very uncomfortable. I know it could just be bloating, gas, or just moving and stretching of internal organs but of course I'm paranoid! I shouldn't read about things like placental abruption online. I've also been having some cramp like sharp pains in the right side of my groin. Any info is appreciated since I'm a first time mom!