Contractions or indigestion????

It feels crazy to say this but I have no idea whether I'm in early labour or just have a dodgy tummy! I was up all night with pain across my whole abdomen and periodic cramps low down. I'm definitely gassy and I've been to the bathroom three times in 12 hours, but it's not giving me any relief from the cramping. The cramps do seem to coincide with my whole stomach going rock hard but I'm not sure if that's just the baby's position! Argh! Any guesses? I don't know if contractions can actually cause the gas?? Anyone else had this confusion?