signs of preterm labor?! help!!

I am 27 weeks and 3 days. And last night my belly continued to get hard and then loosen up again. It done it for about 30 minutes and they were painless. But I also was nauseous and dizzy while this happened and was burning up. I've been having a lot of discharge like stuff coming out of me. I'm afraid my baby will come realllllll early with these signs. I'm only 115 pounds and I'm 16. Is this really normal..?