Premature labor?

I'm 18 weeks and my mom and nurse insist it's too early for premature labor to start, but I really have a feeling that's what it is! I feel intense pressure in the upper part of my vagina, gas pains that come and go, INTENSE back pain that I've never gotten in my life, and a sticky discharge that I've also never expirianced. I don't have classes until 1 pm so I usually sleep until 11 but today I was up at 7 and couldn't go back to sleep. The pain was so intense I thought I was going to throw up. My mom called my nurse because I'm not great on the phone, and my nurse said I'm just carrying the baby in my back and asked no further questions. She just told me to use a heating pad and take a hot shower. I really think I should go in to the hospital because if they catch it early enough they can delay it. These pains started last night at about 11 and now it's almost 11 the next day and they haven't subsided. Has anybody gone into premature labor this early and how did it feel? Is that what this is or something else?