Bad Cramps and Depressed

I'm 16 and pregnant with my first baby I'm expecting a baby boy I'm 20 weeks todat. I've been experiencing terrible cramps just bellow my belly button, they are so unbearable but my doctor is out of the office until Tuesday. I don't know if this is just stress because I have been under a lot of pressure. I really don't have anyone my baby's dad isn't helping me what so ever and my parents want me to move out before the baby comes. I don't have many options and I'm scared. Has anyone had to deal with this kind of cramping I'm really worried for my son. My doctor said I could have many complaication considering how small I am. Please help me.